NordicCNC's build log

[JAZZCNC]

You don't need or want 6 counterbored holes in the lower gantry just use the 3 furthest away from the gantry side and the center front one, you can miss the out the center bolt through the gantry side or put it in but with short threads. Reason being the bolts going through gantry side clash with bolts and it's more important you get good fastening into sides so longer bolts needed. Between them, the gantry is going now were trust me.!

Also with the ball screw spacer plates pay careful attention to fastening bolts and that you can actually access them with BK bearing and screw in place because you'll need to adjust these on the machine when setting alignment etc.

[NordicCnc]

You don't need or want 6 counterbored holes in the lower gantry just use the 3 furthest away from the gantry side and the center front one, you can miss the out the center bolt through the gantry side or put it in but with short threads. Reason being the bolts going through gantry side clash with bolts and it's more important you get good fastening into sides so longer bolts needed. Between them, the gantry is going now were trust me.!

Good notice! I have corrected that now and I will use shorter threaded bolts for the center ones (red arrow).

Also with the ball screw spacer plates pay careful attention to fastening bolts and that you can actually access them with BK bearing and screw in place because you'll need to adjust these on the machine when setting alignment etc.

Yes, I should be able to access those at anytime with current design.



I have also replaced the guide carriages with the wider version, as you suggested.



Thanks for your feedback, I appreciate it!

[JAZZCNC]

I just noticed the size of the pulley and I'm assuming it's to scale.? Try to keep the pulley size small as possible to keep inertia low but at the same time making sure you have enough teeth engaged so don't get jumping teeth or premature wear. If you must use a large pulley then try to use an aluminium one, again to keep inertia low.

[NordicCnc]

I just noticed the size of the pulley and I'm assuming it's to scale.? Try to keep the pulley size small as possible to keep inertia low but at the same time making sure you have enough teeth engaged so don't get jumping teeth or premature wear. If you must use a large pulley then try to use an aluminium one, again to keep inertia low.

Yes, the pulley sizes in the pictures are 20T and 40T. How many teeth need to be engaged at bare minimum? I have not yet found any supplier (I am trying to find those pulley's with taper lock) so for now during the design phase, I went with some sizes I could find on Ebay.

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[jarjar]

Yes, the pulley sizes in the pictures are 20T and 40T. How many teeth need to be engaged at bare minimum? I have not yet found any supplier (I am trying to find those pulley's with taper lock) so for now during the design phase, I went with some sizes I could find on Ebay.

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20T and 40T is good, it's exactly what I use on one axis. Another handy calculator.

I had to deal with the same issue: finding clamping type aluminium pulleys, either HTD or GT3. From my researches those are rare beasts.
HTD taper-lock steel pulleys are relatively common, but add way too much inertia to be considered.

I found 2 options:
- CMT pulleys. The best but expensive, about $60 piece.
- Misumi, with separate taper-lock and pulley. Slightly less expensive, about $40.

[JAZZCNC]

Yes, the pulley sizes in the pictures are 20T and 40T. How many teeth need to be engaged at bare minimum? I have not yet found any supplier (I am trying to find those pulley's with taper lock) so for now during the design phase, I went with some sizes I could find on Ebay.

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Different manufacturers quote different numbers but I think it's roughly 6 teeth before you have to start lowering the HP rating they can handle.

However, your problem will be the smaller pulley size will limit the number of teeth based on it's Boss size and Motor shaft relationship. 20T / 40T sounds about right with a 14mm motor shaft, if it's 19mm shaft then you may have problems.!