[testpilot]

Hello joshendy
Where did you buy CNC parts?

[joshendy]

Nice video. Good luck with your surgery.

Thanks, I appreciate it!

Hello joshendy
Where did you buy CNC parts?

If you see my first post on this topic I have a large write up and mention in there some of the places I brought parts. A big part of the machine is the linear carriages from cncrouterparts.com

[joshendy]

Small update. Recently got myself some new couplings for my CNC. Previously I had jaw type Lovejoy couplings, they were really useless. Good for power transfer but they had a lot of backlash. I had some semi-successful attempts at removing the backlash but I've decided to move on from them.

If you're reading this and thinking of getting Lovejoy jaw type couplings dont do it! Get a one piece zero backlash flexible coupling instead. I managed to get three for $23 USD on ebay, very cheap. They seem a little brittle and weak or maybe its just I'm used to the heavier steel Lovejoy couplings.

Here's a video of them on the CNC:
[ame=http://www.youtube.com/watch?v=WQ7iF5_MTZk]CNC Router - New Flexible Couplings - YouTube[/ame]

You can read more about the couplings on my blog that I've just recently started:
Joshendy's Blog » New Couplings for CNC

[Dylwad]

I just swapped out helical couplers to oldham style to get rid of backlash.... Went from 14 steps of compensation to 3. 3 steps is .00075"


Used lovejoy in the past and just put heat shrink over the ears to make the spider a tight fit with no issues.

If your leadscrews are easy to turn by hand the helicals will be fine except under heavy loads they tend to twist/lag a bit.

The oldhams are very nice, but were $30 each.

[joshendy]

I just swapped out helical couplers to oldham style to get rid of backlash.... Went from 14 steps of compensation to 3. 3 steps is .00075"

Used lovejoy in the past and just put heat shrink over the ears to make the spider a tight fit with no issues.

If your leadscrews are easy to turn by hand the helicals will be fine except under heavy loads they tend to twist/lag a bit.

The oldhams are very nice, but were $30 each.

Thanks for the info. The oldhams look really nice, if I'm not impressed with the helical couplings operation over time I might fork out for the oldhams.

Wow that heat shrink idea is brilliant. I previously was using some rubbery balloon like material streched between the ears and then compressed by the spider but centrifugal force kept throwing it loose. I might go throw some heat shrink on my old lovejoy's and see what I think. Cheers for the idea.

[TheWP]

Hey Josh,

Hopefully you get this post, as I see this thread is a couple years old. I'm in the planning stages of a CNC router right now, came across your design, and found it to be the most similar to what I had in mind. I have started pricing out materials so I can factor that into the design.

My biggest questions are: Is there anything you would have done different on this design? Maybe would have used Thomson linear rails instead, etc...? Did you have any ploblems with alignment? Were you able to cut metal with the machine? Were the linear carraiges okay? How did you bolt the flatbar down (is there a nut on the other side? what about the middle bolt?)

I know this thread is old, but hopefully you get this!

Cheers,

Warren

[TheWP]

Here is a SolidWorks image of what I have so far:

Attachment 262238

I noticed your second design in progress and was just wondering what the weaknesses of this design are before I put so much time/effort/money into this project. Also wondering about the lead screws being 12mm, as through looking across eBay i noticed that 1605's are more common and if them being 12mm is affecting rigidity at all? I also would like to know more about the ballnut you used especially for the Z Axis, as in my SolidWorks project I have a 1 inch clearance.

[joshendy]

Here is a SolidWorks image of what I have so far:

Attachment 262238

I noticed your second design in progress and was just wondering what the weaknesses of this design are before I put so much time/effort/money into this project. Also wondering about the lead screws being 12mm, as through looking across eBay i noticed that 1605's are more common and if them being 12mm is affecting rigidity at all? I also would like to know more about the ballnut you used especially for the Z Axis, as in my SolidWorks project I have a 1 inch clearance.

Hi there, just saw your posts now. If I did my router again today I wouldn't use the square aluminium extrusion for the frame and I wouldn't use the linearrouterparts linear carriages. Assembling the frame was a big pain and ultimately not as rigid as I would have liked and the linear carriages were fairly hard to get adjusted correctly. So what I would do instead is use either a steel frame and weld it together or get 8020 type aluminium extrusion and bolt it together. As for the linear system I'd use supported round linear rails or maybe V rails with V bearings, and I would probably stick with the acme/trapezoidal leadscrews over ballscrews as they work very well in combination with anti-backlash nuts made with delrin. However I've not looked in a while, if ballscrews have come down in price I'd get them.

Yes I bolted down the steel rails with nylon lock nuts on the underside. To reach the middle nut I made a custom tool, just a flat wrench taped to a long metal pole. Sounds ridiculous but worked well. A lot of my build was like this though, less than ideal hacky sort of implementation of things.

My router has definitely been good to me over the last few years. Mostly I've been cutting plastics and wood. It's rigid enough to cut aluminium but I've not done much. My Kress spindle RPM tends to bog down easy so it doesn't make for nice cuts in aluminium. Next router I'd invest in a proper spindle.

[TheWP]

Thanks for your reply,

Glad I haven't had time to work on it yet (just started a new job) because I will take what you said into account. I was definitely looking at the V-Rail system, but noticed that linear rails are fairly cheap on eBay.

As for the frame the 8020- it seems pretty expensive. Anyways, thanks for the advice.