Not sure if you revisit these old videos but here's a personal experience about repairing shafts like the one for the bandsaw. I have tried with success using a Dremel type tool (you have a Proxxon which may be even better, mine flogged its shaft bearings and went to tool heaven) in the tool post of the lathe with a few cutoff discs to give you some width, you know the really thin ones. I have used up to three at a time, with no problems. It is a bit messy, so you have to protect the lathe ways, but if you go easy you can take a few hundredths of a mm to restore the shaft concentric with the bearing shoulders. Just chuck it in a four jaw chuck and if you take a little at a time, the cutoff discs will not wear between cuts so you should be able to cut a consistent diameter. Just make sure you immobilise the rotary tool well in the tool post and use a short mandrel to minimise deflection. Proxxon has a rather good one I have used.
Thanks for your feedback. This is still a task high up on my to do list. Probably the first priority after I finish the Schaublin. Since I have center supports for the Clarkson tool grinder, it will be better for me to do the cylindrical grinding there, but I need to get the two shaft centers concentric with the existing bearing journals first, as I cant regrind them, without them going undersize. I took one shot at it, using the Proxxon in the lathe tool post and dialing in the shaft with the 4J. WIth a little grinding bit in the Proxxon, I reground the center, but didnt get it perfect. I need to find the time to repeat this until that center runs true. Once it does, the actual OD grinding on the Clarkson is pretty trivial.
I would go the same direction with the gear, minimal fussing, do the grind on that shaft, remake the other, and do the last step the previous owner didn't.... Maintenance. Thanks for sharing, Cheers
When slotting keyways I have aways marked out and cut to width. Start with a centerline as long as you can fit onto the part. Next with dividers mark out the key width both sides and again full length. measure from the bore out to indicate full depth. An alternative and superior method is to do all the layout with v blocks and a height gauge. Align the long centerline to the machines axis using a pointed wire. To cut the correct width first cut the center out to almost full depth. Measure with calipers, do not rely on the layout lines. Next continue widening the slot short of final width. Now make a finish cut to the layout-line on one side only. Now move over and take a light cut on the other side and measure the cut width with calipers, teleguage or adj parallel. Calculate the finish pass move over and cut the full width and full depth. check for full width of cut as before. Now move across the slot to clean up the top of the keyway about .1 to .2mm too deep to provide top clearance for the key. By using the one side of the keyway as a reference you will minimise any angular error certainly to the point that a typical key can be simply fitted and an accurate width can be established. It is preferred the key should be a light interference fit in the shaft and a transition to light clearance in the hub. Often it is advantageous to fit a grub screw in the hub over the key to retain the hub and prevent any key rocking. Yes the key you made is too loose and should be corrected even if this means filing a stepped key. Even with pre made key stock it is usual to file to final fit since achieving a proper fit by machining alone is very difficult, especially with slotted keyways. A loose key will eventually flog out the keyways in the shaft and hub. I am sure this blow by blow description is below you but it may help a newbie along the way.
Thnks for they detailed description. I should have put more care into that, and snuck up on the final dimension rather than just set numbers and go for it. Luckily it is a low powered motor, which will probably not see a whole lot of use.
@@RotarySMP Not much use? does that mean the underlying lathe structure is inadequate? I bought a 200x450 Honden lathe many years ago but being a professional machinist the limitations of hobby lathes just frustrated me so I sold it. BTW I can't recommend highly enough the adjustable parallels they are life savers in a number of circumstances. BTW did you get confused with the Austria/Australia thing most of NZ now lives in OZ :)
How about a drawn-cup needle roller for the bush? Might be a bit more scant-lube tolerant. Either running direct on a re-machined pinion shaft journal, or on a pressed-on inner race. Also, I bought a very second-hand 30jaw chuck for my milling machine and drilled holes straight through to bolt it down to the bed. (I only get two bolts, due to the interaction between where it is possible to drill through a chuck and my T-slot spacing)
There is a pressure lubrication system, and that bearing is fed. I think once it starts slogging out, it loses oils pressure and goes pretty fast. Given that the utilisation in my basement is going to be measures in minutes/month, I'll just bring that interstage bushing back into a press fit OD with with a correct tolerance ID. Will easily outlive me. Good idea making a direct mounting mill chuck/vise.
Got a 500w DC Brushless motor with 15k rpm and i dunno how can i control the speed or even start the motor. Probably to strong for the mini lathe i suspect?
That is really not a good match to a lathe. The low speed torque is very low, the design point RPM is unsuitably high, and would need a massive reduction, and they are normally open rotor to allow cooling of the high power, small motor. Swarf will like get in and kill it.
If I dig around in the unused brain cells full of never again used apprenticship knowledge, there can be an advantage with DC motors. I think DC shunt wound motors can have nearly unlimited low speed torque. In practice, I overloaded the original motot and burnt out its windings. It was cheaper to buy a much more powerful three phase motor and VFD than a replacement crappy mini-lathe motor, so I did that.
@@RotarySMP ok thanks. One last question. Is easy/sensible to make a single phase motor variable speed (and how) or better to bin it and go 3phase + vfd.
@@zxspectum I don't know how to make a single phase motor run at variable speed. However many "single phase motors" are actually three phase motors with a capacitor to generate a fake second phase nd thus run. Take the lid of the motor winding connection box and take a look.
OK, easy to say from someone who watches machining videos ... but you seem to have a decent range of gear and skills, so why not design a replacement shaft and helical gear on your cad program and spit them out on your CNC equipment?
I am tempted. Gearorotic has that function to generate 4 axis tool paths to mill gears with small ball mills. I currently dont have a CNC fourth axis, so would need to either motorise the rotary table I have or get a Nikken etc. That is a professional made, ground and harden gear. I have no illusions of duplicating the tolerances of it in my home shop, so the 1/3 remaining tooth on the original shaft may still work better than a bodge up from me .
You needed to show of the power of the Maho again, almost had a heartfailure, love the channel, thx
Glad you are enjoying my videos. Thanks for the feedback.
Awesome channel. You have a great selection of Machines
Thanks for watching. It has taken a while to collect them, and all are worn or have some issues, but I like them.
Not sure if you revisit these old videos but here's a personal experience about repairing shafts like the one for the bandsaw. I have tried with success using a Dremel type tool (you have a Proxxon which may be even better, mine flogged its shaft bearings and went to tool heaven) in the tool post of the lathe with a few cutoff discs to give you some width, you know the really thin ones. I have used up to three at a time, with no problems. It is a bit messy, so you have to protect the lathe ways, but if you go easy you can take a few hundredths of a mm to restore the shaft concentric with the bearing shoulders. Just chuck it in a four jaw chuck and if you take a little at a time, the cutoff discs will not wear between cuts so you should be able to cut a consistent diameter. Just make sure you immobilise the rotary tool well in the tool post and use a short mandrel to minimise deflection. Proxxon has a rather good one I have used.
Thanks for your feedback. This is still a task high up on my to do list. Probably the first priority after I finish the Schaublin.
Since I have center supports for the Clarkson tool grinder, it will be better for me to do the cylindrical grinding there, but I need to get the two shaft centers concentric with the existing bearing journals first, as I cant regrind them, without them going undersize.
I took one shot at it, using the Proxxon in the lathe tool post and dialing in the shaft with the 4J. WIth a little grinding bit in the Proxxon, I reground the center, but didnt get it perfect. I need to find the time to repeat this until that center runs true. Once it does, the actual OD grinding on the Clarkson is pretty trivial.
Thanks for the video. Interesting as always. Keep safe and stay well.
Thanks, you too!
I would go the same direction with the gear, minimal fussing, do the grind on that shaft, remake the other, and do the last step the previous owner didn't.... Maintenance.
Thanks for sharing,
Cheers
That's the plan! I took one shot at it already, but couldn't get the centers ground back in accurately enough. Need to try again there.
When slotting keyways I have aways marked out and cut to width. Start with a centerline as long as you can fit onto the part. Next with dividers mark out the key width both sides and again full length. measure from the bore out to indicate full depth. An alternative and superior method is to do all the layout with v blocks and a height gauge.
Align the long centerline to the machines axis using a pointed wire. To cut the correct width first cut the center out to almost full depth. Measure with calipers, do not rely on the layout lines. Next continue widening the slot short of final width. Now make a finish cut to the layout-line on one side only. Now move over and take a light cut on the other side and measure the cut width with calipers, teleguage or adj parallel. Calculate the finish pass move over and cut the full width and full depth. check for full width of cut as before. Now move across the slot to clean up the top of the keyway about .1 to .2mm too deep to provide top clearance for the key.
By using the one side of the keyway as a reference you will minimise any angular error certainly to the point that a typical key can be simply fitted and an accurate width can be established. It is preferred the key should be a light interference fit in the shaft and a transition to light clearance in the hub. Often it is advantageous to fit a grub screw in the hub over the key to retain the hub and prevent any key rocking.
Yes the key you made is too loose and should be corrected even if this means filing a stepped key. Even with pre made key stock it is usual to file to final fit since achieving a proper fit by machining alone is very difficult, especially with slotted keyways. A loose key will eventually flog out the keyways in the shaft and hub.
I am sure this blow by blow description is below you but it may help a newbie along the way.
Thnks for they detailed description. I should have put more care into that, and snuck up on the final dimension rather than just set numbers and go for it. Luckily it is a low powered motor, which will probably not see a whole lot of use.
@@RotarySMP Not much use? does that mean the underlying lathe structure is inadequate? I bought a 200x450 Honden lathe many years ago but being a professional machinist the limitations of hobby lathes just frustrated me so I sold it. BTW I can't recommend highly enough the adjustable parallels they are life savers in a number of circumstances. BTW did you get confused with the Austria/Australia thing most of NZ now lives in OZ :)
Tony Is really good at accents isnt he :-)
Thanks for watching.
@@RotarySMP this guy has way prettier hands 😜
This is where Tony and Rotary fell out actually, even though Tony's Maho wasn't really damaged.
This has become a wonderful series. Very entertaining.
PS. If it's not bent, it's boring.
Thanks for watching.
How about a drawn-cup needle roller for the bush? Might be a bit more scant-lube tolerant. Either running direct on a re-machined pinion shaft journal, or on a pressed-on inner race.
Also, I bought a very second-hand 30jaw chuck for my milling machine and drilled holes straight through to bolt it down to the bed. (I only get two bolts, due to the interaction between where it is possible to drill through a chuck and my T-slot spacing)
There is a pressure lubrication system, and that bearing is fed. I think once it starts slogging out, it loses oils pressure and goes pretty fast. Given that the utilisation in my basement is going to be measures in minutes/month, I'll just bring that interstage bushing back into a press fit OD with with a correct tolerance ID. Will easily outlive me.
Good idea making a direct mounting mill chuck/vise.
F for the boring bar :)
Not good. ;(
You can try to buy a pair of standard straight tooth gears and remake that thin shaft
I could, but will first use the remaining 1/3 toothed gear. Thanks for watching.
Thanks for sharing.
5:34 oh no
Hi, interesting video thanks for sharing.
Glad you enjoyed it
Y, Z, how much difference could it really make? :P
That is what I thought as well. Turns out it matters more than expected :(
You must be an engineer.
Aircraft mechanic. Thanks for watching.
Got a 500w DC Brushless motor with 15k rpm and i dunno how can i control the speed or even start the motor.
Probably to strong for the mini lathe i suspect?
That is really not a good match to a lathe. The low speed torque is very low, the design point RPM is unsuitably high, and would need a massive reduction, and they are normally open rotor to allow cooling of the high power, small motor. Swarf will like get in and kill it.
11:22 boom
Hi, regarding 3 phase versus a DC motor, is there a pro and con over the two, do you less stall with 3 phase?
If I dig around in the unused brain cells full of never again used apprenticship knowledge, there can be an advantage with DC motors. I think DC shunt wound motors can have nearly unlimited low speed torque.
In practice, I overloaded the original motot and burnt out its windings. It was cheaper to buy a much more powerful three phase motor and VFD than a replacement crappy mini-lathe motor, so I did that.
@@RotarySMP ok thanks. One last question. Is easy/sensible to make a single phase motor variable speed (and how) or better to bin it and go 3phase + vfd.
@@zxspectum I don't know how to make a single phase motor run at variable speed. However many "single phase motors" are actually three phase motors with a capacitor to generate a fake second phase nd thus run. Take the lid of the motor winding connection box and take a look.
🔧😊👍
OK, easy to say from someone who watches machining videos ... but you seem to have a decent range of gear and skills, so why not design a replacement shaft and helical gear on your cad program and spit them out on your CNC equipment?
I am tempted. Gearorotic has that function to generate 4 axis tool paths to mill gears with small ball mills. I currently dont have a CNC fourth axis, so would need to either motorise the rotary table I have or get a Nikken etc.
That is a professional made, ground and harden gear. I have no illusions of duplicating the tolerances of it in my home shop, so the 1/3 remaining tooth on the original shaft may still work better than a bodge up from me .
That thing looks like a nightmare
This video is pretty old. I can't recall what nightmare we are looking at :)
hello friend, this belt doesn't slide, because you don't use V belt
I used a Poly-Vee belt.