HobbyCNC Router Plans

[RJM]

Hello,

I am just building a router from the HobbyCNC plans. Has anyone built this router?

Any comments, suggestions, changes that anyone might have?

[CNCadmin]

Here is my version-
http://www.cnczone.com/photopost/sho...cat=500&page=1

[wjbzone]

I used the basic design, but made it a little bigger and made it mostly from aluminum.

The plans do not include thrust bearings to limit your backlash. You may want to add that.


http://www.intergate.com/~wjb1/wjbzone/wjbzone-cnc.html

Bill

[RJM]

Hi,

I was planning on using larger leadscrews to carry a bigger load so I could put something on other than a dremel if required. I am not sure what you mean by thrust bearings to prevent the backlash.

I thought the anti backlash nuts did that. I am new to all of this, so you have to pardon my ignorance.

Also, If I use something bigger than a dremel, would the 1/2" drill rod and igus linear bearings suffice for the Y axis?

[wjbzone]

The anti-backlash nuts minimize any play between the nut and the leadscrew. Thrust bearings keep the leadscrew from moving axialy when direction changes.

The HobbyCNC design intends for the stepper motor shaft to keep the leadscrew from any axial movement. This works fine for the lightweight wood design. More machine weight or a loose motor shaft can cause more backlash than you want to compensate for with the software.

I got the 125 oz-in motors and I could push/pull the motor shaft about 0.045 in. The thrust bearings (several designs in this forum) can be placed at each end of the leadscrew to bear the axial thrust of the screw rather then depending on the motor bearings to take that load.

Also:
I used 1" drill rod for my X axis and 3/4 for Y and Z. The Igus bearings are doing great. I had to hone the holes I pressed them into to get the right fit. I mounted a Porter Cable 1.75 hp router on my machine.

Bill

[RJM]

Bill,

Thank you for your information. That helps immensely. I will do a search for the thrust bearings.

One other question, did you use the same Kerk Motion leadscrews, or go up in size for the dynamic load? Or did you use something else?

Thanks again.

Richard

[wjbzone]

Richard,
I used these:

Ballscrew - 5/8 OD x 0.200 lead. McMaster Carr PN 5966K26. (cost $1.07/inch)

Ballscrews Nuts - MMC PN 5966K16 (cost $20.63 each)


I bought a 72" length of screw that was enough for all three axis.

(The screw and nut are made by Thompson Saginaw Inc.)

Bill.

[RJM]

Hi Bill,

I ordered up the ballscrews and nuts. They look good. One other question I had was do you have some sort of cover on the screw or a wiper for the nut to keep the dust out?

I noticed they are quite expensive, or is there a cheaper solution that you know of?

Richard

[wjbzone]

Richard,

I don't have any suggestions for what to use for a dust cover. My X axis is shielded by the table and stays fairly clean. The Y and Z axis are exposed, but above the cutter. Also the air from the cutter tends to blow dust away.

The dust that does collect on the screw, I just blow away.

I'm sure some dust has gone thru the ballscrew. It does not seem to be a problem.

Bill

[pack rat]

That McMaster ballscrew went up to $50. It looked promising.

[Hobbiest]

As far as wipers go, get a couple of packages of those felt pads that you put on funiture feet. Get the ones with the adhesive backing, cut a hol in the center equal to the di of the screw between the threads (minor di, I think), and stickem on.
Whats with all the talk of drill rod? Did Cranky start this? Don't know if its cheaper, but CRS is usually good to about .004, from what Dave Gingery says in his Build a Machine Shop From Scratch series. www.lindsaybks.com/dgip/djgbk/indes.html, check it out, fun stuff!

[RJM]

I bought the ballscrew from Reid Tool. It was $36 ish for a 36" piece. Nuts were $23 I think.

Thanks for the suggestions regarding the wiper.

Richard