[poorfarmer25]

Hello I am having an unusual problem with my rack and pinion router table. When I am raster cutting anything it leaves these lines on the material opposite of the axis I am cutting
The top pocket was cut with 1/8 tapered end mill from left to right of the photo while the right pocket that is perfectly smooth was cut on the Y axis.

I got this problem after upgrading my bushings from bearings on the cnc router parts website, I have since tramed my spindle and readjusted/checked all
the r&p parts, changed collets, and replaced the bit a 1/4 ball nose makes exactly the same line. cutting wood in different places on the table does not matter neither does the speed unless you run really really slow.

I emailed the distributor and even they were stumped.



Attachment 206750

[awerby]

It looks like a grain effect. Try cutting it different ways, like all-climb or all-conventional instead of rastering back and forth. You might also try orienting the material 90 degrees off how it is or cutting another material with different or no grain.

On the other hand, it could also be something wrong with the X axis of your router. If you see these same lines in plastic cut along the X axis, then you can probably ascribe it to vibration affecting the sliding motion of that axis, most likely due to bad bearings or bushings.

Andrew Werby
www.computersculpture.com

[poorfarmer25]

Attachment 206752

I have tried in different pieces of oak and cedar they all do the same I have not had great luck climb cutting, rastering at 90 (Y axis )does work fine, but I like to cut with the grain when I can.( also your site looks neat)

[louieatienza]

Attachment 206752

I have tried in different pieces of oak and cedar they all do the same I have not had great luck climb cutting, rastering at 90 (Y axis )does work fine, but I like to cut with the grain when I can.( also your site looks neat)

your spindle might be out of tram; chucl a piece of ground drill rod in and check perpendicularity along both axes...

[poorfarmer25]

I have tramed it, it was needing it but did not help my problem.

[ger21]

Looks to me like your getting some type of vibration when traveling along the X axis.

[poorfarmer25]

Just an update I believe I found my problem one of the pulleys on my x axis had a set screw that was just loose enough to give it some slop but not enough to let it move when pushing on the gantry.

[CarveOne]

An improperly tensioned R&P drive can cause similar patterns.

[neilw20]

Try and cut some circles. It will be obvious if there is backlash. Eyes can detect quite small aberrations in circles.
It could also be flexing of the cutter/spindle.

[poorfarmer25]

I am still having problems with this if anyone else has any ideas, Its been broke for about a month now. I have disassembled my gantry and make sure everything rolls evenly, replaced the dumpster nut and used a dial indicator on my collet to check for bearing play in my spindle, I even tried a different computer.

One thing I did notice today is that sometimes when I move my X axis the motors sound a little off, they make a high frequency noise for a second or two after stopping. But do not jerk at all. Could this mean I need to adjust the trim on my drivers??

Thanks for the responses! I live in the middle of nowhere and don't have anyone else to ask about this.

[louieatienza]

I am still having problems with this if anyone else has any ideas, Its been broke for about a month now. I have disassembled my gantry and make sure everything rolls evenly, replaced the dumpster nut and used a dial indicator on my collet to check for bearing play in my spindle, I even tried a different computer.

One thing I did notice today is that sometimes when I move my X axis the motors sound a little off, they make a high frequency noise for a second or two after stopping. But do not jerk at all. Could this mean I need to adjust the trim on my drivers??

Thanks for the responses! I live in the middle of nowhere and don't have anyone else to ask about this.

Looking at this again, it does seem the problem arises in a periodic fashion. I would check the pinions on both sides to makes sure they run concentric and there is no play with their bearings. I'd recheck the drive belts and see if they have proper tension (too tight is just as bad as too loose.) I'd also check the spring tension of the r&p interface; again too tight is not good either. Check all the bearings in all your bearing blocks to ensure they spin freely without play. You moght want to put ferrite chokes on your stepper wires (near the drive side) if there's any interference; the long axis has longer cables which might be more prone to interference. Personally, however, you'll get witness marks no matter what; and they're more obvious when going cross-grain. You can try a bit with a tip radius (like .020-.030) instead of square and see if that helps. In any case you should be scraping or sanding ANY mill marks on wood; this isn't a piece of steel or aluminum.

[poorfarmer25]

I dissembled my gantry again and checked everything for proper tension and slid it back and forth to make sure it rolled well, bearings are in good shape. I don't think that this could be a mechanical problem any more, I have ran it with lots of slop and never had any problems near this bad, also the lines are really precise.

I have also tried running my spindle at different speeds without any effect.

I shut off my 12 volt power and my water circulating pump and vac. Just to check if they were the culprit but no change.I have ordered 7 ferrite cores I hope to get them soon.

[Falcon69]

Those lines look identical to what a piece looks like after it comes out of the Planer, or worse, a surface belt sander where the belt was worn down and not sanding properly.

Did you try using a sharper cutting bit? Maybe take less off at a time?

I also developed this problem with an old planer I had. The belts were loose, causing the feed rate to kind of stutter as the piece went in.

It sounds to me like louie has the right idea. A pinion or rack is loose, or tension is too loose or too tight.

[poorfarmer25]

That's exactly what it looks like. I been using two new bits both good quality 1/8 tapered ball nose and 1/4 ball nose but still no luck . What I have done to check tension was to reassemble the aluminum base stepper and all make sure it slides well and then bolt it onto the gantry. The belts are just snug with about 1/10 play.

[Falcon69]

Is it just me, or do those pinions look worn, like alot.

[poorfarmer25]

I put the old pinions back on for troubleshooting, the third picture shows the new gears I think. The newer gears have bearings instead of bushing's and roll easier.

[poorfarmer25]

-update- I have replaced all the bearings, pinions, mdf table,spindle nut, collet and a lot of other stuff but am still getting lines. Could the rack be bad? I have had this machine close to 3 years and have not greased the rack and pinions at all to avoid contamination. I'm not sure I want to put anymore money in it but I would really like to see it run again.

[ger21]

My guess would either be the rack or the rails the bearings are rolling on. I could be wrong, though.