Clever application of 3D printing

[old mart]

Just as well there were 3 as the first is not very good, the second is fitted to the Atlas and the third is unfinished, but fits the bull gear nicely.

[old mart]

I have got hold of a 20mm thick piece of nylon 6, 200mm by 100mm. This was cut into 3 parts and I have got almost to the stage of producing the threads to fit the bull gear. The three parts were attached to the 9" faceplate which has multiples of 6 tee slots and slots. They are held 30mm above the plate surface to enable the milling cutter to reach and the inside bore diameter is the same as the root diameter of the bull gear. I made a plug gauge out of an old vee pulley which can be held on the axis of the rotary table to refit the pieces as two of them have to be removed for access to mill the one still attached. The other problem was the reach from the spindle. I had a piece of ground steel bar 18mm diameter and 260mm long which would fit in an R8 collet and I bored one end 10mm to take a 10 degree tapered milling cutter. At that length, the runout is 0.004" which won't matter with soft nylon, fortunately. I haven't got any further, so far.

[old mart]

I printed it with 40% infill and 4 exterior walls, which made the teeth solid (no infill). It appears to be plenty strong in this application with the forces spanning the layers. I tried it several times so far and there are no marks on the teeth or the end where it bears against the head stock. So I'm a happy camper and don't have to worry about wrecking the bull gear

If you use it every time you remove the chuck and use a strap wrench on the chuck, it and the bull gear should last many years.

[Rich Carlstedt]

...................... so you might want to try PETG or reorienting the part in the slicer ...................

+1 as an example of solving problems with 3 D
Rich

[Rich Carlstedt]

Took a college course in 3 D Printer design and it's amazing what can be done in the design , especially using stress analyses from Solidworks CAD Tools.
We had to design and redesign a concept many times to improve strength and then used the Material Lab to destroy our work
Design, Honeycomb fill, Material, PROCESS and stress analysis all go into a good part that will exceed your expectations.

The "gear plugs" are a great idea for HSM'ers

Rich

[Stu]

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.

I printed it with 40% infill and 4 exterior walls, which made the teeth solid (no infill). It appears to be plenty strong in this application with the forces spanning the layers. I tried it several times so far and there are no marks on the teeth or the end where it bears against the head stock. So I'm a happy camper and don't have to worry about wrecking the bull gear

[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.

[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.

[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.

[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.

[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.

[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.

[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.

[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.

[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.