Clever application of 3D printing

[old mart]

I have just noticed a number of ebay ads for these locking devices for SB, Atlas and some other lathes.

https://www.ebay.co.uk/itm/203526392...r=503910632470

[J Tiers]

Reminds me of the Briggs tool that holds the flywheel/fan.

If it holds up it ought to work fine. Holds enough teeth that it should be OK, and it is not likely to strip the bull gear, as 1) it should "give" until all teeth are about even as far as force applied, and 2) it should fail before the teeth anyhow..

[old mart]

I like the thought of being to actually hold the zamak bull gear on the Atlas without stripping all the teeth off. I will have a word with my friends with printers, the postage across the pond is more than I'm willing to spend.

[Stu]

This inspired me to make one for my Craftsman/ Atlas.

[RB211]

It gives me a smile as more of you accept 3D printers.

[old mart]

Stu, I recon I can machine one like yours on the rotary table on the mill. The tooth count is 69 and the OD is 6", I would get hold of a slab of plastic 20mm thick and 200mm square. With enough teeth engaged and soft material, they wouldn't have to be perfect.

[Paul Alciatore]

I wonder if the CAD files for them may be available from Thingverse or some other network source.

No I just looked on Thingverse and could not find anything like them. I may make one and upload it.

[Stu]

I wonder if the CAD files for them may be available from Thingverse or some other network source.

No I just looked on Thingverse and could not find anything like them. I may make one and upload it.

Paul, I'd be happy to share mine.

[repoman]

I've had a couple ABS parts printed for use on my mill (spindle lock) and they do not last very long from regular use.

[psomero]

I've had a couple ABS parts printed for use on my mill (spindle lock) and they do not last very long from regular use.

is that surprising? the stresses of a spindle lock (presumably a pin in a bore) wouldn't work well if it was a part milled from a solid chunk of ABS bar stock, either.

[old mart]

I have a block of nylon 6, 20mm thick, 200 X 100mm on order from ebay, only £12 delivered, to play with. It could make 4, so I have plenty of chances to get it right. I must have a look at the dividing plates for the RT, 69 or increments of 5 degrees 13 minutes. I was thinking of having the axis of the RT horizontal and standing the section of nylon off so that a cutter could reach the concave turned surface. I recently needed to reach into a difficult area and put an er11 collet with a 16mm shank into an er25, which worked well with a sharp cutter and small cuts. I don't have the exact cutter profile, but do have a 5 degree taper one with the right diameter end. Stu has about 15 teeth on his and that looks plenty strong enough for me.

[RB211]

On the flip side, the 3D printed part costs .50 cents to print in material, I’d use PETG. When it breaks, make another.

[repoman]

is that surprising? the stresses of a spindle lock (presumably a pin in a bore) wouldn't work well if it was a part milled from a solid chunk of ABS bar stock, either.

The fragility of the ABS printed part was surprising, my mill is small and the spindle lock doesn't require a large amount of torque. If the part had been made of ABS stock I have no doubt it would still be working. The 3D lock I was using was about 4x4x1 inch, it took something like 10 hours to print. I'm just saying my experience with things like these where there are repeated loads (even small ones) on 3D printed stuff can be a bit iffy. I think there was much more engagement with the part I had for my mill than the teeth on this part for a lathe lock.

[old mart]

Printed parts are often honeycombed inside to save material which could weaken them in high stress conditions. In this particular application, the teeth would be in solid form and having the stress spread over 15 teeth seems plenty strong enough to me. A splndle lock for a mill would probably be at a smaller radius which multiplies the forces.

[thin-woodsman]

The fragility of the ABS printed part was surprising.

ABS is known to delaminate so you might want to try PETG or reorienting the part in the slicer if it failed along layer lines - if you haven't tried that already. Some of the different infill options provide greater strength, e.g. the honeycomb design. Assuming your spindle lock isn't actively being battered by the monkey operating the mill in your absence, the 3D part should be strong enough - I would expect it to wear out fast, not break, so might be a problem with the printing.