Rear Parting Tool Holder For Your Lathe - Part 2
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- Опубликовано: 15 дек 2022
- In this episode I finish off the machining on the malleable iron base and machine the steel riser which will eventually clamp the tee type parting blade in place. I also show some new features of TouchDRO which help you to visualise coordinates for machining slots, pockets and tenons.
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Very satisfying to watch this machined part emerge from the chunky piece of stock - looking forward to the next step and of course when it all gets the Preso 'icing on the cake' finishes.
Thanks. I will be parkerising all the steel parts and the iron riser has been cleaned up on a 120 grit sanding belt to remove the machining marks. I have never parkerised iron before. It is supposed to work but it is a big heavy part and the parkerising works best when the temperature of the part comes up close to the boiling point of water. It probably won't rust as readily as the steel parts though.
Regards,
Mark
Hey. You stole my micrometer... lol watched part 1 and part of 2. First 2 vids I've seen of yours, will be back for more.
Thanks. A lot of people thought I had stolen it from Joe Pie! It was actually my son, James that engraved those micrometers after I loaned them to him when he was doing his apprenticeship.
Regards,
Mark
@@Preso58 my grandfather, my dad, my son, and myself all have the same initials.
When it’s a big expense complex part, measure 10 times and cut once 😂. Seasons greetings and a shiny new year 🎉
Nice work Mark. I fully concur with your coolant gripe on the mill. I've made up 4 tinplate walls that cunningly contain chips and coolant. The walls clip together and are free standing.
Gday Preso, the new features on the TouchDRO are fantastic, I’ve found setting up for simple jobs like bolt hole patterns is simple, im really looking forward to the next instalment, brilliant job as always mate, cheers
Thanks Matty. So you got the TouchDRO update? I like the graphical nature of the interface. The new version has provision for a touch probe too.
Regards,
Mark
@@Preso58 no I haven’t yet but looking at yours the new version looks great
Man, that touch dro looks awesome! Pretty clever !
Useful features on the "TouchDRO" application bordering on CNC toll compensation, great introduction when a user migrates, If they do of course.
Nice work, looking forward to seeing further videos.
The malleable iron is a great vibration dampener material.
Thanks for sharing.
Regards John
Internal damping was one of the characteristics that I was looking for in the malleable iron. Plus it's just nice to work with.
Regards,
Mark
Excellent work, Mark. I'm really enjoying this series. At 28:35 You fit the block to the T-slot on the larger tool rest and there's some interference in the last few microns of engagement. I suspect some radii need to be added to the top surface along the T-slot in order to clear the never quite perfect corner fillets left by the mill when milling out the tenon of the tool holder. It's been weeks since you've posted this video, so no doubt you've already worked it out.
Finally got to watch this episode :-) The end mill that you sharpened seemed to be cutting better now, than on the day you sharpened it.
This is a massive tool holder (surely minimal chatter). Great features on TouchDRO.
Thanks, I have finished all of the parts now and I have installed it on the lathe. I've done a few preliminary cuts on some aluminium but I am a bit reluctant to find the limitations of the parting blade. That is going to be part that will fail but you will get to see the final episode shortly.
Regards,
Mark
@@Preso58 Thanks for this preliminary info! Yep, that parting blade is thin, but without geometry misalignments and no chatter, it can be very effective. In any case, you can always use an insert parting blade, which should be significantly stronger.
Ciao Mark, maybe in the same time we ( me and you) were using that pararrel blocks to take a measure on a video, incredible! I love to see how rigid Is your milling machine during the work, with my milling machine that block at minimum twice the time you did! Also your DRO Is very different from the standards DRO like mine, i really enjoyed watching your part 2! Ciao Mark, Alberto
Thanks Alberto. I am still getting used to the Bridgeport and I am learning to push it a lot harder than I did when I first got it into the shop. Having sharp cutters makes a huge difference. The TouchDRO has some nice features and having a graphical display works well for me.
Regards,
Mark
Great work Mark. The parts came together perfectly. It'll be great to see it all working.
Regards.
Steve.
Great work again Mark! Is nice seeing the rough steel transforming so nicely. Also loved the sound of the wildlife in the background 🙂
Maybe I should invest in a TouchDRO one day. I hear nothing but good about it.
It has some nice features and the app can be updated as bugs and fixes are corrected. I do have a much dumber two axis DRO on my lathe but it is a bit more difficult to interpret with such a limited alphanumeric display.
Regards,
Mark
Very nice! Lots of chips today! Thanks!
I just finished cutting a number of T-slots in aluminum using a woodruff key cutter and it worked very nicely. I just set my speed and feed rate by feel and sound. I used a bit of lubricant as well whereas you didn't need to in cast iron.
I must admit I am not one of those wizards who can calculate chip loads and feeds and speeds on the fly. I think that listening to the cut and looking at the way the chips are coming off is a good indication though.
Regards,
Mark
Lovely work Mark 👍👍👍
Looking very nice Mr P. Wishing you and yours a very Merry Christmas!! Cheers for now.
Your beginning operation to cut the slot consisted of milling side to side at n mm increments. I would have brought the cutter centerline to just shy of the edge of the part and plunged to 21 mm deep. Follow that by successive plunge milling operations until you're through the width of the block. Cut from one end to the other at 21 mm deep to have the slot central on the part. Then do your off-sets and cut the slot to 22 mm deep. I found this to be faster than successive passes.
Thanks for the feedback. What I did probably appeared clumsy and I often look back and see ten different and probably better ways to achieve the same result. However, I am not looking for efficiency so much as trying to achieve an accurate result. I tend to be very conservative in terms of speeds, feeds and depths of cut. I am sure that the Bridgeport is capable of much heavier cuts and I am slowly working out what it's limitations are.
Regards,
Mark
Thank you Mark for another interesting and informative episode. I must check out those new features on Touch DRO. Your machining is a joy to watch. 👏👏😀👍
Merry Christmas from Scotland Mark!
Great work Presso. Love watching your work..
Nice work. I'm really liking that TouchDRO.
Some top quality machining there. Its coming along nicely Mark. I like you big chamfer tool. I need to get one of those.
I first saw that style of cutter being used on West Welds channel. I have been reminded to avoid using the bottom of the insert as the surface speed is much lower nearer to the point.
Regards,
Mark
Looking great :)
Really nice work as always, I quite like the App driven DRO. That's neat. Happy Down Under Christmas.
Mark like you I always have a clean pair of undies whenever I tried parting off; it has a very large pucker factor. In the past I made a leg for a grooving tool (Winkys design) but was never happy with it. Spurred on by your project I made one myself this arvo. I started with a large chunk of aluminium (I know I will come to regret that) and bolted this to 2, 8mm tapped holes in the cross slide using socket head cap screws. The aluminium block is the same height as the steel rises (replacing the compound) on the front of the cross slide. I then used a spare AXA QCTP and mounted this on the aluminium riser. I have 3 different parting blade solution I have used in the past, a 3mm insert blade tool, a 2mm grooving tool and HSS blades. Each one was adjusted so that it was upside down and the cutting edge was on center height. Imagine my disappointment when NONE of them worked; I tried all of the belt permutations for each of the tools and none of them gave anything While I enjoyed the shed time I would judge none of them a success. I hope yours works better than mine!
Michael, that sounds disappointing indeed. I made a tool many years ago from some welded hot rolled steel sections which bolted on to the back of the cross slide and it too was a failure. Looking back now it was far too light and I didn't have any way of machining the mating surfaces accurately so it was probably not seated down onto the cross slide accurately. The tool bit chattered quite badly and I just gave up and scrapped the whole contraption. I am hoping that the new version has enough mass and is accurate enough to be at least an improvement on the front mounted solutions I am using at present. I should be finished mid week and of course it could all be for nothing but I badly want it to succeed.
Regards,
Mark
@michaellinahan7740
Probably an overlooked factor is bellmouthing of the chuck jaws like Rob Renzetti has done his most recent video on. on 'uncorrected' jaws the clamping is only effective on the inside, so the true unsupported length of material is much greater than it looks. Correcting this is not a trivial task though. A quick fix would be to clamp some paper between the jaws and the workpiece near the outside. Also it is a good check to see if this improves the situation. When all is said and done, any machine has its limitations, I have abused a tiny Hobbymat lathe when I was a teenager before moving on to serious machines.
Looking great Mark.
Thanks Randy.
Regards,
Mark
Senior moment there Mark😉 The No of teeth has no influence on cutting speed, only feed rate. While on the subject it is better to chamfer cut closer to the cutter shoulder as the point has close to zero surface speed.
Thanks for the feedback. I am very much a "suck it and see" machinist. If it looks and sounds right I am happy. I do agree with your observation about the chamfering tool though. I will do that next time.
Regards,
Mark
Since the cutting blade is mounted upside down, the way you designed the clamp means that most of the force is transferred to the flexure portion and set screws rather than the solid block. You may want to think about how to increase the rigidity, maybe providing the tool clamping force from the bottom instead.
One of the points of this design is that any flexure reduces both the top rake and the depth of cut- unloading the cutter. A balance is found. This is similar to the (conventional cut) top pivot point parting cutter. Indeed, I intend building a similar unit with flexure deliberately built in.
Jason, I want to try the inverted tool approach but of course I have no way of verifying it will work without trying it our under real world conditions. I take your point about the lack of rigidity above the cutting edge of the tool but it cannot be any worse than having the cutter deflect down and inwards as it does in a conventional front mounted tool. We shall know within the week if it's a success or an embarrassing failure!
Regards,
Mark
@@Tensquaremetreworkshop Getting the flex load forces (and damping) where it helps rather than just creating chatter seems more difficult than just making it as solid as possible.
@@Preso58 Not sure if I made my point well. I have no objection to the overall design, just pointing out that with the conventional tool blade holder, the force on the blade is transmitted to the fixed side of the tool holder. The force concentration is at the solid front edge, and the flexure portion has leverage advantage at the rear, whereas your tool holder has the flexure and adjuster screws, especially at the front, taking up all that cutting force. If you make that top surface solid and clamp the tool from the bottom side, I would expect it to be more rigid.
@@Bakafish Actually I mentioned just today that the Colchester manual shows a design which is inverted, the fixed surface is on the top and the clamping screws come from the bottom. I will iterate on this design using a standard insert type tool holder which has a block mounted on the side. It fits in a slot in the holder and is secured by two M8 screws mounted in the horizontal plane. The clamping block is then supposed to be clamped in the tool post just as is shown in this video. Personally I do not like the tool overhang, a more rigid connection to the tool post is preferred. It is only a small step to make a 4-way indexing rear tool post, on one of the sides a special interface (i.e. tenon/ 2x M8) to fit the tool holder directly. I would like to use other positions for a tailstock turret and possibly chamfering and threading tools.
I think the radius of the block fitting into the T slot should be relieved. Then you will be able to move it by hand. A chamfer on the base block T slot top edge would do it.
Fantastic work Mark! I hope to build a small shop where I live in Thailand. I have no idea where to find resources in Thailand but there must be somewhere. You are a great engineer!
Looking good mark, coming together nicely.
THANKS MARK
Your work is top-notch!
I have a Colchester Student which is not my main lathe (it's just sitting around) but it's a very nice machine. I have downloaded the manual that shows the rear toolpost. I am in the process of making one for my German Gema LZ 160 which I use all the time. The nice thing is that it already has two T-slots in the casting of the cross slide, perpendicular to the main machine axis. This makes it very easy to set the tool holder in a position suitable for the workpiece geometry.
One remark I would like to make is that the Colchester toolpost also has inverted the clamping surface and screws, so that the cutting forces are not pushing against the screws. The nice way you made this in two parts, a main body and the holder on top will make it easier to change the latter.
Very good idea to use malleable iron, will research this further. I can buy grey cast iron in several qualities cut to size from a Dutch supplier but don't know yet what the cost is.
Keep up the great work, looking forward to the next video.
Yes, having tee slots in the cross slide would be wonderful. The Myford Super 7 lathe has this feature and it makes the machine very versatile. I actually modelled and exact replica of the original Colchester rear tool post with the two tool slots but it seemed unnecessary for what I wanted to achieve. The malleable iron can be purchased under the name "Durabar".
Regards,
Mark
@@Preso58 This material looks very promising for many applications.
In fact as a coincidence, I had to make some replacement conveyor chain links and it just so happened that off-the-shelf threaded malleable iron fittings were the perfect size for the bushings, with minimal excess material. It's a bit of an emergency repair but I expect them to last for many years since the conveyor sees very little use. A bit of the root of the thread remains which I think will be very good for holding lubricant. Since the ductile cast iron does not hold (much) 'free' graphite (flakes) its self-lubricating properties are not as good as regular cast iron it appears, although working with it will give you black hands. We'll just run it and evaluate, gonna be interesting. Another point is that the bushing outer surface slides on a guide rail and this will produce wear in the form of a flat surface developing eventually. The current hardened bushings (may be surface hardened/ carburized) have worn almost through the full thickness but this has taken more than 40 years. Manufacturer's claim is that ductile is more wear resistant than grey cast though.
I have looked at the Durabar website, they have no sales channel in Europe so I will have to find an alternative.
Many thanks
Hi Mark good progress on this project, inverted tooling has an advantage on well used lathes as the head bearings ware, the load pushes againest the bottom of the bearing to reduse movement in a vertical position
in some casees of head ware it will help reduce chatter.
regards
ken
Thanks Ken. I have now finished all three parts of the build and I have tried it out but I am very nervous about using power feed. Ultimately, that is the aim but I want to use it properly with the camera running. If it can cut without chatter and I can relax and use the power feed I will take that as a win.
Regards,
Mark
Thanks for sharing and Merry Christmas to you and your wife.
Great content Merry Christmas
Enjoyed….
Nice work!
It seems to me that the tooth cutting the T-slot on the left side didn't know anything about the tooth cutting the T-slot on the right side, so wouldn't be in a position to negotiate a doubling of the surface speed. Or that's a thought! :)
You gotta work with what you've got. 😁 I tend to shoot from the hip when selecting chip loads and surface speeds. If it sounds right it's good enough for me.
Regards,
Mark
Looking good. Have you considered mist coolant for the mill, a lot less mess but a bit air hungry.
I do have a shop made mist coolant system on my small CNC mill. It works well but it makes a huge mess. The air blows the chips everywhere but on aluminium it does keep the cutters cool and it blows the chips out of the cut so they don't get welded back onto the part and the cutting edges. The flood coolant on the Bridgeport does a good job and I did find two holes in the front and back of the vice that were allowing the coolant to drip off the table and onto the floor. I have since plugged those holes and it's making less mess now.
Regards,
Mark
Whilst it is neat that your DRO system does the sums for you- for slots like this you can do the calculation in your head much faster. For complex cuts I tend to make a DRO map of co-ordinates and mount it on the mill- just follow the numbers as fast as you can dial them. Less time on your feet...
That is just me being a nerd! I must say though that I am a very visual learner. Mathematics for me is torture but if I can seen a visual representation I can relax and just use the digital readout as confirmation that I am on track.
Regards,
Mark
👍 Thx for the vid.
Looking great so far👍 Did you chamfer the top of the slot at all? Just wondering if there's a small radius at the end of the cutter you used to make the tenonwhich would leave a small fillet at the base, which would lead to binding as you tighten the post down. Cutting a small chamfer at the top of the slot would mitigate that, maybe letting the post slide freely when not screwed down (and sit flatter and more rigidly when screwed down, spreading the load more)
I will fit all the parts when they are all made. The 12mm carbide end mill that I was using is probably a bit worn on the lower end of the helical flutes so the top of the slot will be wider than the bottom. I did chamfer the top of the slot with a file but it might need a bit of scraping to get it sliding nicely.
Regards,
Mark
Think I'd mill the block to hold the cut off tool it would be much more ridgid.
Enjoy your content…
Hello Mark,
Nicely done... enjoyable viewing, thank you. What finish will be be putting on the tool holder.
Take care.
Paul,,
Paul, I will be parkerising the steel parts. I am not sure about the malleable iron base. I believe you can parkerise cast iron but I haven't tried it yet.
Regards,
Mark
I have looked into it and I did make a mist coolant system for my small CNC mill. The genuine fog buster units are probably the best but they are very expensive (in Australia). The flood coolant system was already installed on the Bridgeport. It just needed some new hose and a clamp for the Locline. I need to refine the way I use it. I am finding places where the coolant overflows from the vice but I think it can be fine tuned a bit and be useful.
Regards,
Mark
😊💪👍👍👍
You didn't consider just clamping the parting tool directly in the tool holder that you just made ?
Would get the blade closer to the centre bolt
I did think about that. I want the design to be capable of taking different styles of parting blades or perhaps threading tools too. If it is successful I can fit a parting blade permanently on the other side of the riser.
Regards,
Mark
"... just gives you visual confirmation you're not about to do something stupid." - Around here we call that a 'sanity check' and use such checks quite often - and STILL make mistakes.
The capacity for my brain to make the totally incorrect choice when setting up for a non reversible operation is truly amazing. Sanity checks reduce the error rate but it's never zero😁
Regards,
Mark
😎😎😎😎😎😎😎😎😎
Ahh, James, you rascal!
I know! Evidently he didn't trust his co-workers.
Regards,
Mark
@@Preso58 and he also forgot your initials… ;)
Mark do you know if the updated software for Touch DRO will work on Samsung Galaxy 7 tablet.? I love my Touch DRO but would also like to add the upgrade.
I believe it will work on all Android operating systems after V4.0. The Beta version is available on Play Store now.
Regards,
Mark
@@Preso58 Thanks Mark. After I finish the job that is on my mill now, I will try to update it.
How important is it to use malleable iron for this project? It is rather expensive.
FWIW, I suspect that ordinary "gray" iron will do for that block, BUT the mess of dusty swarf generated will be HUGE. OTOH, somebody with a home foundry setup could make a pattern and cast it in "gray" iron that requires only "modest" machining to final size.
The rear post on my Colchester looks factory and is all steel rather than cast. If using cast, I personally would use maliable to reduce the possibility of the 'T' breaking out. Cast is good in compression but not tension.
Mark, I had never machined anything from malleable iron before and there was an Australian metal supplier who just happened to have the correct size in stock for this project. I did ask an Australian home foundry operator if he was interested in casting from some patterns of my design but he lived in another state and the cost of shipping would have made it even more expensive. He also doubted that he could melt enough iron to make the parts I wanted. I did have some steel that was close to the size I needed but it was a very hard grade of material and it would have been a challenge to work with.
Regards,
Mark
Conservative…. your chips look too fine for a 12mm carbon. Why is there so much noise in the spindle?
That's how Bridgeports sound. They have straight cut gears in the drive to the spindle. You are also probably hearing the rotary phase converter.