hello mr gelbart a concept so clear as you explained "peel mode" shoud be more emphasized in all welding literature as why some welds, even ones made following code, fail miserably under service. the welding manuals assume that we are welding rigid components and that linear forces are applied when the reality is not always that. i know it will help me in making safer weldments. thanks for sharing these explanations for people like me that can`t reach formal education.
Thank You for a very inspiring video! I have by now watched most of Your videos and found gems of information in all of them useful for my own prototyping shop. Your description of water jet for prototyping taking advantage of the slight taper is very interesting. I would add one more type of glue that that I have used a lot for prototyping in recent Years. There are several grades of heat curing epoxy that can be cured at fairly low temperatures in a lab oven. No mixing, high strength, easy dispensing from small syringe bottles and syringes, unlimited open time and quick turnaround time are some reasons I use this type of adhesive more than any other nowadays. During heating these epoxies thin and flows momentarily very much like solder. The type I prefer is Permabond ES 566. Stored the stuff for 2 years in the fridge without problems although the datasheet says 6 months. Hope You have the time to make some more videos like the previous ones. Best Regards, Erik Isberg
Builders of composite aircraft,place the resin and hardener,place them in a box with a incandescent light bulb.The heat makes them more fluid and therefore,easier to mix and spread easier.They also use a epoxy pump that meters the epoxy accurately.
Mr Gelbart, Its likely that you are very busy, but please continue these classes, even it its once in blue moon. As you read in the comments, Its highly valued by scientists engineers and hobbyists alike. Thank you sir
It's cheaply manufactured flat and it's very resistant to warping over time due to fluctuations of temperature. Even a mass machined granite countertop is surprisingly flat, and large calibrated plates are only a few thousand dollars per plate for an incredible amount of surface flatness. Smaller calibrated plates are easily sub 100 dollars and that's just not something you will get with anything else.
I got'alot'a love for the world but Dan is what is missing form these new times. Someone truly loves being a Machinist and true master of his trade that is willing to teach and let us in his beautiful shop. He is always in his videos in a great mood, at least to me & makes me want to absorb every single byte of knowledge that he speaks! He is exactly like my Brother expect my Brothers leave critical points out so you have to go through HE'LL?
Hi Dan, you are the most incredible shop teacher I never had. My parents wouldn't let me take shops. I have read your Linkedin and it is pretty amazing. I have a feeling that you met my late father in law. He was involved in the science exhibit game and I remember him talking about the technology of Creo after a visit to your facility. Love your videos because they inspire others take on new avenues in their business pursuits. Hope you are well.
I think you provide more valuable information per minute than any other video. Thank you. I'm here for the flexture but am really enjoying the whole series. Incredible.
If you are considering silicone as an adhesive or potting compound in electronics prototyping, be aware there are two types of curing chemistry:- a) "RTV" cure, and b) neutral cure. Always use a neutral cure silicone. RTV cure silicones release acetic acid during and after the curing process - this will over several months to several years, corrode away any metal, particularly copper and any fine wires. Silicone sold especially for bonding glass is the worst in this aspect. In general, if the container or packaging does not specifically state "neutral cure", it isn't - it's RTV (acid) cure. Sometimes electronic circuits are potted as a means of protecting against moisture or to avoid issues with vibration. Be aware that in such cases there cannot be air circulation and the power dissipation of parts must be evaluated on that basis. A better solution in most cases is what is known as "conformal coating".
*Building Large Structures with Adhesive Bonding: A Prototyping Perspective* * *0:07** Adhesive Joint Preparation:* Demonstrates preparing two adhesive-bonded joints (peel strength and shear strength) using 5-minute epoxy. Tip: For longer working time with fast epoxy, mix it on a cold surface. [From powaybob's Comment: Using a cold soda can bottom can be helpful for this.] * *1:49** Introduction to Large Structure Building:* Focuses on building large, temporary structures for experiments or research setups using adhesive bonding as an alternative to welding. * *2:17** Welding Drawbacks:* Highlights two main drawbacks of welding: * Difficulty in mastering welding techniques. * Significant distortion caused by welding heat, requiring machining for correction. * *3:14** Adhesive Bonding Advantages:* Suggests adhesive bonding as a suitable alternative when high strength is not critical, but stiffness is required. * *3:27** Scaled Prototyping:* Recommends building a 1/10th scale model using water jet cut aluminum plates and pipes to test and refine the design before building the full-scale structure. * *4:19** Leveraging Water Jet Taper:* Exploits the slight taper of water jet cuts for self-jigging and easy assembly/disassembly of the structure. * *5:05** Disassembly with Heat:* Notes that adhesive-bonded structures can be disassembled by heating them (e.g., with a torch or in an oven) to around 150°C (300°F) to soften the epoxy. * *5:38** Limitations of T-Slot Extrusions:* Explains why t-slot extrusions, despite their ease of assembly, lack rigidity for applications requiring high precision or accuracy. * *7:27** Bracket Design and Wedging:* Demonstrates designing and integrating brackets into the structure, utilizing the water jet taper to create a wedge-like effect for secure locking without adhesive. * *8:33** Importance of Flatness:* Emphasizes the importance of a flat reference surface (like a granite plate) for assembling structures that require co-planarity. * *9:30** Flexure Clamps for Removable Parts:* Introduces the concept of flexure clamps for securing removable parts (e.g., granite beam) without applying localized stress. * *11:19** Flexure Clamp Construction:* Explains how to create a flexure clamp by cutting a slot and using a tapered pipe thread and plug for expanding and clamping. * *12:50** Advantages Over Set Screws:* Highlights the superiority of flexure clamps over set screws, as they distribute pressure evenly and avoid potential damage to brittle materials. * *13:56** Adhesive Joint Design Principles:* * *Shear Mode:* Emphasizes designing adhesive joints to operate in shear mode for maximum strength. * *Tension Mode:* Tension mode is acceptable but weaker than shear mode. * *Peel Mode:* Strongly advises against designing joints that will experience peel stress, as this leads to very weak bonds. * *16:01** Peel Mode Failure Explanation:* Explains why peel mode joints fail: Stress is concentrated along a single line (zero area), leading to almost instant failure. * *17:45** Common Lab Adhesives:* Lists four essential adhesive types for a lab environment: * *Epoxy:* For general-purpose bonding, especially where quick curing time is desired. * *Silicone RTV:* For high-temperature applications, elasticity, and strong bonding to glass and ceramics. [From keithammleter3824's Comment: Use neutral cure silicone to avoid corrosion issues with RTV cure silicones.] * *Polyurethane:* For flexible bonds, gap filling, and bonding to rubber or other flexible materials. * *Spray Contact Cement:* For bonding large sheets with uniform adhesion. * *21:58** Cautions about Cyanoacrylates (Super Glue):* Recommends avoiding cyanoacrylates (super glue) in scientific work due to their brittleness, outgassing, and negative effects on optics and some plastics. [From ChrisLeeX's Comment: Super glue can be particularly harmful to optics.] * *24:01** Thermal Expansion Considerations:* Warns about the high thermal expansion coefficients of plastics and adhesives compared to metals. Recommends careful consideration when bonding dissimilar materials, especially if precise alignment is crucial. * *24:43** Wedge Bonding and Optical Levers:* Explains how adhesive wedges used for alignment can cause significant angular changes with temperature due to the magnified effect of thermal expansion through optical levers. [From NomenNescio99's Comment: Using high-quality epoxies with proper mixing ratios and curing procedures can dramatically increase strength.] I used gemini-1.5-pro-exp-0801 on rocketrecap dot com to summarize the transcript. Cost (if I didn't use the free tier): $0.09 Input tokens: 23696 Output tokens: 1024
Everytime I finish watching one of Dan’s videos, I can’t help but have a grin from ear to ear! The knowledge, wisdom and critical design tips this man is sharing is absolutely mind blowing
I don't agree on the PU vs epoxy statement. Quick setting epoxies are notoriously bad on pretty much all properties compared to the slow setting epoxies. Strength can also significantly improved by proper curing, which usually includes a period of increased temperature over a period of time after the first initial curing, aka "baking" - times and temperatures varies. And it's extremely important to have the proper mixing ratio between epoxy and hardener if you want the full performance, eyeballing simply isn't good enough - either a measuring syringe or use a scale and remember to use the weight mixing ratio. If you are using quality epoxy, proper surface preparations and correct curing, there is no PU based glue that gets even close to that strength, regardless of the type of strain the bond is exposed to, epoxy can even outperform welding in some applications. Once you leave the consumer grade epoxy and start working with more professional glues, always avoid contact with your skin - wear gloves whenever you use a real epoxy. Almost all epoxies are solvent-free today so there is rarely any need for breathing masks, but the hardeners can cause severe allergic reactions on skin contact - and the risk increases with multiple exposures. In fact the PU based glues are becoming more and more rare today, for most wood applications PVA based "carpenters glue" have superior performance, in general construction work the MS-polymer based glues have much better performance than the previous generation of PU-based construction glues and for any high performance application epoxy is almost always the best choice. Many PU-glues are frequently touted as "gap filling", but they really aren't - at least not if you want a strong bond. The problem is that accused gap-filling property is based on the PU-glues bubbling or foaming when curing, there is a very high probability that the gap will be filled with air to a large part and not glue, and although air has many good properties - strength isn't one of them. Let me continue to diss PU-glue a little more, once cured PU-glue will be very moisture resistant - it can even withstand being submerged in water for long periods of time, but the curing process of PU is based on moisture/water. If you have materials that contains moisture or are in an a moist environment the curing process can get so bubbly and foamy that your workpieces can be pushed apart unless they are fixated properly and you'll end up with a very weak joint. The alleged flexibility of PU-glues is not unique, epoxies can be made to have a very wide range of E-modulus. For some types of epoxy you can even vary the flexibility by adding different amount of hardener. But I wholeheartedly agree that CA-glues should be avoided except for some niche applications. And in the name of honesty, some materials won't give you a good bond with epoxy unless you do some very special surface preparation, aluminum is worth mentioning in this category. Sorry for the rant, but I really like epoxy - it's capable of so much more than most people think.
Really interesting post, thank you. I have bonded sanded aluminium to plastic with steel filled epoxy before and the result was nice, but I guess it's generally not very challenging to glue together thin objects with a large surface area. I'm a bit surprised about the low opinion on cyanoacrylate glues. I've read elsewhere that epoxy tends to only bond mechanically to most plastics, while superglue and two parts acrylate adhesives makes actual chemical (covalent) bonds.
Love your videos! Aren't solvents good "glues" for plastics? Like acetone for ABS or THF for PLA etc. They evaporate and just leave you with the bonded plastic.
Solvents are good adhesives but only for perfectly fitting parts as they can not fill any gaps, as they evaporate. A better solution is to dissolve some of these plastics in their solvents and use this as an adhesive. This is what the commercial plastic cements are, like ABS or PVC cement.
@@dgelbart How would you achieve six face coplanarity? Two options I am considering are: (1) clamp large reference blocks inside during gluing to cause the faceplates to be parallel and then rotate and knock flat against the table as you did (2) cut side plates with finger joints for assembly jigging, resulting in a fully boxed structure. Then, clamping the structure using studs through all faces. If I did not have the tubes additionally, the joints may be in peal in certain directions? Would you worry about the waterjet taper angle causing issues? I imagine it would cancel out as long as I am consistent with all smaller edges facing inwards? My goal is to align pre-bored holes for a flanged strain-wave gear motor with crossed roller bearing output on one side and an outboard deep groove ball bearing on the other side. I plan to integrate a flexure on the crossed roller bearing gearhead side to account for angular misalignment and rely on the deep groove ball bearing's clearances (and good assembly alignment) on the other side. For the outboard bearing, I would use a flanged mounting plate with clearance holes. I would align it using a laser on arm in a mill's spindle until the beam touches both holes nicely while spinning. My thought is the structure will be good within a thou, the laser alignment will get me within tenths, and the flexure will prevent any over constraint? This is a bit out of my comfort zone and I would love your advice! Thank you for these videos, as well! They have been incredibly useful.
Am i correct when i assume the shear test is biased by the fact you compress in the direction of the taper and thus need additional force to cause movement. A more honest shear test would be to apply force on the opposite side and only measure shear strength of the epoxy bonding. I love your video's and almost lost a keyboard from drooling over your high precision air bearing cnc lathe/grinder, what a beauty !
No, the shear test did not rely on the taper as at this thickness of aluminum there was practically no taper and in any case the male part was machined and had no taper.
How can one glue PP or PE or other low surface energy plastics? All I can find is either very expensive and needs a primer or has to be activated with plasma, which you normally don't have, or is there a way to activate it with DIY methods?
Best method (better than plasma) is sandblasting, as it also creates roughness. Second best (equivalent to plasma) is scrubbing with Ajax/Comet/Bar Tenders Friend. In both cases adhesive has to be applied in an hour and joint designed for shear mode. Regardless of method, strength will be low. Dan
@@dgelbart Thank you for your quick reply. I have been so frustrated so many times when a part made of PP or PE broke and no high strength bond was possible. Well at least today I can 3D print the part now. Well today I think, maybe melting with additional material to fix it, is that a good idea?
Great to see the Gressel vise. I bought two of the AX 125 as well as the drilling vise Ecopos with guide rail, which is a brilliant invention no one should be without. Money was never spent better.
Hi Mr. Gelbart, thank you again for you generously showing us your knowledge. Please allow me to ask three questions concerning the flexure clamp: (1) For the flexure clamp using pipe taper thread, do we use female pipe taper thread paired with male "taper" plug (with slanted threads)? Or male "straight" plug (with straight threads)? I imagined that female taper + male taper would not lead to much material deformation, but I could be wrong. (2) Is there a rule of thumb on how far away the flexure clamp slit should be from the thing we want to clamp? I guess it is subject to some trial and error (with difference in material thickness and such), but I find it difficult to estimate how much flexure I can get on the final 1:1 large structure based on the flexure I get on the 1/10 model we build to try. (3) Approximately up to how large of structure would you still recommend the flexure clamp? For structures bigger than that, what can be good options? (I'm imagining trying to make the structure you made to hold graphite into a room-size structure holding a large graphite beam or metal beam.)
See previous reply about taper. As far as size and scaling, he only rule is not to exceed the elastic limit of the material when the clamp deflects to maximum deflection.
Thank you Mr. Gelbart for your prompt reply! I'm not entirely sure but I think your response below says that the male part has a straight thread, not tapered. I hope that I understand it correctly. And thank you for the guideline about elasticity.
@@dgelbart Thank you so much for the confirmation!! Very excited and grateful to see your latest video. Thank you for your generosity on sharing knowledge.
Thank you for sharing your knowledge. i love these videos and would like to know more. do you know any more sources (books websites etc.) also tips for making things on a low budget.
I just received the book today Dan. Going to be nerding out for the next couple days. Any other books you would recommend. Also I'm wondering where I could learn more about flexture design.
sir, with reference to 22:19 about Cyanoacrylate glue, is it good to bond broken coffee mug handle to the mug? is the porosity in coffee mug ceramic an issue with 2 part epoxy? What is the best glue for this coffee mug ceramic and forces getting applied to its handle? Thank you
hello mr gelbart a concept so clear as you explained "peel mode" shoud be more emphasized in all welding literature as why some welds, even ones made following code, fail miserably under service. the welding manuals assume that we are welding rigid components and that linear forces are applied when the reality is not always that. i know it will help me in making safer weldments. thanks for sharing these explanations for people like me that can`t reach formal education.
Thank You for a very inspiring video!
I have by now watched most of Your videos and found gems of information in all of them useful for my own prototyping shop.
Your description of water jet for prototyping taking advantage of the slight taper is very interesting.
I would add one more type of glue that that I have used a lot for prototyping in recent Years. There are several grades of heat curing epoxy that can be cured at fairly low temperatures in a lab oven. No mixing, high strength, easy dispensing from small syringe bottles and syringes, unlimited open time and quick turnaround time are some reasons I use this type of adhesive more than any other nowadays. During heating these epoxies thin and flows momentarily very much like solder. The type I prefer is Permabond ES 566. Stored the stuff for 2 years in the fridge without problems although the datasheet says 6 months.
Hope You have the time to make some more videos like the previous ones.
Best Regards, Erik Isberg
I am just initiating to see your videos. Very educational and hands on. Thank you.
Builders of composite aircraft,place the resin and hardener,place them in a box with a incandescent light bulb.The heat makes them more fluid and therefore,easier to mix and spread easier.They also use a epoxy pump that meters the epoxy accurately.
12:32 I love how he would rather grind his hex key down rather than pay for imperial tools...
Mr Gelbart, Its likely that you are very busy, but please continue these classes, even it its once in blue moon. As you read in the comments, Its highly valued by scientists engineers and hobbyists alike. Thank you sir
Why is granite so flat tho?
Or isit the way its been processed..?
It's cheaply manufactured flat and it's very resistant to warping over time due to fluctuations of temperature. Even a mass machined granite countertop is surprisingly flat, and large calibrated plates are only a few thousand dollars per plate for an incredible amount of surface flatness. Smaller calibrated plates are easily sub 100 dollars and that's just not something you will get with anything else.
Regarding mixing epoxy on a cold surface to increase working time. Mix it in the indented bottom of a cold, full, soda can. Saw this tip somewhere.
Concentration of useful information is coming to infinity in these videos. Thanks to the author.
I got'alot'a love for the world but Dan is what is missing form these new times. Someone truly loves being a Machinist and true master of his trade that is willing to teach and let us in his beautiful shop. He is always in his videos in a great mood, at least to me & makes me want to absorb every single byte of knowledge that he speaks! He is exactly like my Brother expect my Brothers leave critical points out so you have to go through HE'LL?
Hi Dan, you are the most incredible shop teacher I never had. My parents wouldn't let me take shops. I have read your Linkedin and it is pretty amazing. I have a feeling that you met my late father in law. He was involved in the science exhibit game and I remember him talking about the technology of Creo after a visit to your facility. Love your videos because they inspire others take on new avenues in their business pursuits. Hope you are well.
I think you provide more valuable information per minute than any other video. Thank you. I'm here for the flexture but am really enjoying the whole series. Incredible.
If you are considering silicone as an adhesive or potting compound in electronics prototyping, be aware there are two types of curing chemistry:-
a) "RTV" cure, and b) neutral cure.
Always use a neutral cure silicone. RTV cure silicones release acetic acid during and after the curing process - this will over several months to several years, corrode away any metal, particularly copper and any fine wires. Silicone sold especially for bonding glass is the worst in this aspect. In general, if the container or packaging does not specifically state "neutral cure", it isn't - it's RTV (acid) cure.
Sometimes electronic circuits are potted as a means of protecting against moisture or to avoid issues with vibration. Be aware that in such cases there cannot be air circulation and the power dissipation of parts must be evaluated on that basis. A better solution in most cases is what is known as "conformal coating".
*Building Large Structures with Adhesive Bonding: A Prototyping Perspective*
* *0:07** Adhesive Joint Preparation:* Demonstrates preparing two adhesive-bonded joints (peel strength and shear strength) using 5-minute epoxy. Tip: For longer working time with fast epoxy, mix it on a cold surface. [From powaybob's Comment: Using a cold soda can bottom can be helpful for this.]
* *1:49** Introduction to Large Structure Building:* Focuses on building large, temporary structures for experiments or research setups using adhesive bonding as an alternative to welding.
* *2:17** Welding Drawbacks:* Highlights two main drawbacks of welding:
* Difficulty in mastering welding techniques.
* Significant distortion caused by welding heat, requiring machining for correction.
* *3:14** Adhesive Bonding Advantages:* Suggests adhesive bonding as a suitable alternative when high strength is not critical, but stiffness is required.
* *3:27** Scaled Prototyping:* Recommends building a 1/10th scale model using water jet cut aluminum plates and pipes to test and refine the design before building the full-scale structure.
* *4:19** Leveraging Water Jet Taper:* Exploits the slight taper of water jet cuts for self-jigging and easy assembly/disassembly of the structure.
* *5:05** Disassembly with Heat:* Notes that adhesive-bonded structures can be disassembled by heating them (e.g., with a torch or in an oven) to around 150°C (300°F) to soften the epoxy.
* *5:38** Limitations of T-Slot Extrusions:* Explains why t-slot extrusions, despite their ease of assembly, lack rigidity for applications requiring high precision or accuracy.
* *7:27** Bracket Design and Wedging:* Demonstrates designing and integrating brackets into the structure, utilizing the water jet taper to create a wedge-like effect for secure locking without adhesive.
* *8:33** Importance of Flatness:* Emphasizes the importance of a flat reference surface (like a granite plate) for assembling structures that require co-planarity.
* *9:30** Flexure Clamps for Removable Parts:* Introduces the concept of flexure clamps for securing removable parts (e.g., granite beam) without applying localized stress.
* *11:19** Flexure Clamp Construction:* Explains how to create a flexure clamp by cutting a slot and using a tapered pipe thread and plug for expanding and clamping.
* *12:50** Advantages Over Set Screws:* Highlights the superiority of flexure clamps over set screws, as they distribute pressure evenly and avoid potential damage to brittle materials.
* *13:56** Adhesive Joint Design Principles:*
* *Shear Mode:* Emphasizes designing adhesive joints to operate in shear mode for maximum strength.
* *Tension Mode:* Tension mode is acceptable but weaker than shear mode.
* *Peel Mode:* Strongly advises against designing joints that will experience peel stress, as this leads to very weak bonds.
* *16:01** Peel Mode Failure Explanation:* Explains why peel mode joints fail: Stress is concentrated along a single line (zero area), leading to almost instant failure.
* *17:45** Common Lab Adhesives:* Lists four essential adhesive types for a lab environment:
* *Epoxy:* For general-purpose bonding, especially where quick curing time is desired.
* *Silicone RTV:* For high-temperature applications, elasticity, and strong bonding to glass and ceramics. [From keithammleter3824's Comment: Use neutral cure silicone to avoid corrosion issues with RTV cure silicones.]
* *Polyurethane:* For flexible bonds, gap filling, and bonding to rubber or other flexible materials.
* *Spray Contact Cement:* For bonding large sheets with uniform adhesion.
* *21:58** Cautions about Cyanoacrylates (Super Glue):* Recommends avoiding cyanoacrylates (super glue) in scientific work due to their brittleness, outgassing, and negative effects on optics and some plastics. [From ChrisLeeX's Comment: Super glue can be particularly harmful to optics.]
* *24:01** Thermal Expansion Considerations:* Warns about the high thermal expansion coefficients of plastics and adhesives compared to metals. Recommends careful consideration when bonding dissimilar materials, especially if precise alignment is crucial.
* *24:43** Wedge Bonding and Optical Levers:* Explains how adhesive wedges used for alignment can cause significant angular changes with temperature due to the magnified effect of thermal expansion through optical levers. [From NomenNescio99's Comment: Using high-quality epoxies with proper mixing ratios and curing procedures can dramatically increase strength.]
I used gemini-1.5-pro-exp-0801 on rocketrecap dot com to summarize the transcript.
Cost (if I didn't use the free tier): $0.09
Input tokens: 23696
Output tokens: 1024
Everytime I finish watching one of Dan’s videos, I can’t help but have a grin from ear to ear!
The knowledge, wisdom and critical design tips this man is sharing is absolutely mind blowing
Wow, I did not know super glue was so harmful to optics. Thank you for covering that.
Best videos on RUclips, really make my day. So much secrets and tips in every episode. Please, make more of them!
I can confirm that machines made from e-bar are not rigid. Everything moves no matter how tight you torque everything down.
I’d like to add an acrylic adhesive to his list: 3M DP805 or similar.
I am learning lot new things
from your every word ...
Not a 3D printer in sight.
I almost feel like this should be re-titled "Adhesives" instead of "Large Structures"; so many good tips though!
I don't agree on the PU vs epoxy statement.
Quick setting epoxies are notoriously bad on pretty much all properties compared to the slow setting epoxies. Strength can also significantly improved by proper curing, which usually includes a period of increased temperature over a period of time after the first initial curing, aka "baking" - times and temperatures varies.
And it's extremely important to have the proper mixing ratio between epoxy and hardener if you want the full performance, eyeballing simply isn't good enough - either a measuring syringe or use a scale and remember to use the weight mixing ratio.
If you are using quality epoxy, proper surface preparations and correct curing, there is no PU based glue that gets even close to that strength, regardless of the type of strain the bond is exposed to, epoxy can even outperform welding in some applications.
Once you leave the consumer grade epoxy and start working with more professional glues, always avoid contact with your skin - wear gloves whenever you use a real epoxy. Almost all epoxies are solvent-free today so there is rarely any need for breathing masks, but the hardeners can cause severe allergic reactions on skin contact - and the risk increases with multiple exposures.
In fact the PU based glues are becoming more and more rare today, for most wood applications PVA based "carpenters glue" have superior performance, in general construction work the MS-polymer based glues have much better performance than the previous generation of PU-based construction glues and for any high performance application epoxy is almost always the best choice.
Many PU-glues are frequently touted as "gap filling", but they really aren't - at least not if you want a strong bond. The problem is that accused gap-filling property is based on the PU-glues bubbling or foaming when curing, there is a very high probability that the gap will be filled with air to a large part and not glue, and although air has many good properties - strength isn't one of them.
Let me continue to diss PU-glue a little more, once cured PU-glue will be very moisture resistant - it can even withstand being submerged in water for long periods of time, but the curing process of PU is based on moisture/water. If you have materials that contains moisture or are in an a moist environment the curing process can get so bubbly and foamy that your workpieces can be pushed apart unless they are fixated properly and you'll end up with a very weak joint.
The alleged flexibility of PU-glues is not unique, epoxies can be made to have a very wide range of E-modulus. For some types of epoxy you can even vary the flexibility by adding different amount of hardener.
But I wholeheartedly agree that CA-glues should be avoided except for some niche applications.
And in the name of honesty, some materials won't give you a good bond with epoxy unless you do some very special surface preparation, aluminum is worth mentioning in this category.
Sorry for the rant, but I really like epoxy - it's capable of so much more than most people think.
Really interesting post, thank you.
I have bonded sanded aluminium to plastic with steel filled epoxy before and the result was nice, but I guess it's generally not very challenging to glue together thin objects with a large surface area.
I'm a bit surprised about the low opinion on cyanoacrylate glues. I've read elsewhere that epoxy tends to only bond mechanically to most plastics, while superglue and two parts acrylate adhesives makes actual chemical (covalent) bonds.
Superb Sir
In Feel Mode ... Geometrically Zero Area.....
Best one is 3 Dimensionsional geometrical Constrain....
Love your videos! Aren't solvents good "glues" for plastics? Like acetone for ABS or THF for PLA etc. They evaporate and just leave you with the bonded plastic.
Solvents are good adhesives but only for perfectly fitting parts as they can not fill any gaps, as they evaporate. A better solution is to dissolve some of these plastics in their solvents and use this as an adhesive. This is what the commercial plastic cements are, like ABS or PVC cement.
Would you use the approach shown at ~13:00 if the primary goal is the rod's parallelism rather than the top surface of the plate's coplanarity?
Yes, you design the clamp to press on the less important surface against references on the other surfaces.
@@dgelbart How would you achieve six face coplanarity? Two options I am considering are:
(1) clamp large reference blocks inside during gluing to cause the faceplates to be parallel and then rotate and knock flat against the table as you did
(2) cut side plates with finger joints for assembly jigging, resulting in a fully boxed structure. Then, clamping the structure using studs through all faces. If I did not have the tubes additionally, the joints may be in peal in certain directions? Would you worry about the waterjet taper angle causing issues? I imagine it would cancel out as long as I am consistent with all smaller edges facing inwards?
My goal is to align pre-bored holes for a flanged strain-wave gear motor with crossed roller bearing output on one side and an outboard deep groove ball bearing on the other side. I plan to integrate a flexure on the crossed roller bearing gearhead side to account for angular misalignment and rely on the deep groove ball bearing's clearances (and good assembly alignment) on the other side. For the outboard bearing, I would use a flanged mounting plate with clearance holes. I would align it using a laser on arm in a mill's spindle until the beam touches both holes nicely while spinning.
My thought is the structure will be good within a thou, the laser alignment will get me within tenths, and the flexure will prevent any over constraint?
This is a bit out of my comfort zone and I would love your advice!
Thank you for these videos, as well! They have been incredibly useful.
@@dimitrischreiber9140 For your application it is best to bore the holes after gluing housing together.
Am i correct when i assume the shear test is biased by the fact you compress in the direction of the taper and thus need additional force to cause movement. A more honest shear test would be to apply force on the opposite side and only measure shear strength of the epoxy bonding. I love your video's and almost lost a keyboard from drooling over your high precision air bearing cnc lathe/grinder, what a beauty !
No, the shear test did not rely on the taper as at this thickness of aluminum there was practically no taper and in any case the male part was machined and had no taper.
How can one glue PP or PE or other low surface energy plastics? All I can find is either very expensive and needs a primer or has to be activated with plasma, which you normally don't have, or is there a way to activate it with DIY methods?
Best method (better than plasma) is sandblasting, as it also creates roughness.
Second best (equivalent to plasma) is scrubbing with Ajax/Comet/Bar Tenders Friend.
In both cases adhesive has to be applied in an hour and joint designed for shear mode.
Regardless of method, strength will be low.
Dan
@@dgelbart Thank you for your quick reply. I have been so frustrated so many times when a part made of PP or PE broke and no high strength bond was possible. Well at least today I can 3D print the part now. Well today I think, maybe melting with additional material to fix it, is that a good idea?
@@AlJay0032 OK method, not perfct. That is what I usually do.
My dad used to say, there are guys that can weld and guys who think they can weld,,,lol.
Great to see the Gressel vise. I bought two of the AX 125 as well as the drilling vise Ecopos with guide rail, which is a brilliant invention no one should be without. Money was never spent better.
I also have the Gressel milling vise and agree with your sentiment.
Extremly intresting and usefull!!
i love this guy
Can I translate this series into other languages and upload to RUclips? With links to original of course
So educational!
Sure. I'll be honoured.
Did you make any translation videos?
Hi Mr. Gelbart, thank you again for you generously showing us your knowledge. Please allow me to ask three questions concerning the flexure clamp:
(1) For the flexure clamp using pipe taper thread, do we use female pipe taper thread paired with male "taper" plug (with slanted threads)? Or male "straight" plug (with straight threads)?
I imagined that female taper + male taper would not lead to much material deformation, but I could be wrong.
(2) Is there a rule of thumb on how far away the flexure clamp slit should be from the thing we want to clamp?
I guess it is subject to some trial and error (with difference in material thickness and such), but I find it difficult to estimate how much flexure I can get on the final 1:1 large structure based on the flexure I get on the 1/10 model we build to try.
(3) Approximately up to how large of structure would you still recommend the flexure clamp? For structures bigger than that, what can be good options?
(I'm imagining trying to make the structure you made to hold graphite into a room-size structure holding a large graphite beam or metal beam.)
See previous reply about taper. As far as size and scaling, he only rule is not to exceed the elastic limit of the material when the clamp deflects to maximum deflection.
Thank you Mr. Gelbart for your prompt reply! I'm not entirely sure but I think your response below says that the male part has a straight thread, not tapered. I hope that I understand it correctly. And thank you for the guideline about elasticity.
@@jeanapp_ Both male and female have tapered threads.
@@dgelbart Thank you so much for the confirmation!! Very excited and grateful to see your latest video. Thank you for your generosity on sharing knowledge.
Thank you for sharing your knowledge. i love these videos and would like to know more. do you know any more sources (books websites etc.) also tips for making things on a low budget.
Read this: www.abebooks.com/servlet/SearchResults?sts=t&tn=building+scientific+apparatus
A bargain at $4 including shipping.
I just received the book today Dan. Going to be nerding out for the next couple days. Any other books you would recommend. Also I'm wondering where I could learn more about flexture design.
@@motionsick www.slideshare.net/RaphaelOliveiraSantos/building-scientific-apparatus
See page 63 :)
@@dgelbartthank you so much it's a useful book.
sir, with reference to 22:19 about Cyanoacrylate glue, is it good to bond broken coffee mug handle to the mug? is the porosity in coffee mug ceramic an issue with 2 part epoxy? What is the best glue for this coffee mug ceramic and forces getting applied to its handle? Thank you
Epoxy.
+Dan Gelbart thank you sir :)
I have had a good experience with glueing ceramic items with PVA (white wood glue). I did some destruction testing and it was not easy to break.
Why am i here! RUclips wtff