Bowed extrusion

[weslambe]

When I put my 5x8 prs together I noticed that the extruded aluminum rails were bowed about 1 1/2 inches or so. I didn't measure and assumed that the supports underneath pulled the bow out and that all would be rainbows and butterflys. I also couldn't install one of the legs because of an aluminum bump in the channel. I did turn the leg over and was able to install the leg but that makes me wonder about the overall quality.

I get chatter and can't seem to get rid of it. Here's what I've done so far to try to troubleshoot:

1. Let motors hang from x car and moved back and forth. Found that the table wasn't level doing this. Still get bumpy feeling even when rolling by hand and motors still hanging.

2. Purchased 78" level and made sure machine is level so that's no longer a question. Still bumpy.

3. jacked up gantry about 1/4 to see if roller bearings work correctly. They do.

4. measured the rails outside to outside and get 77 13/16ths at the end of the rails but I can't seem to get the rails to spec in the center. There, I get around 77.84375 instead of the required 77.8125. That's not much but I've got to get rid of this chatter.

To do:

remove table top
check rail to rail for 73.5"
move rails if needed.

What I don't want to do:
completely tear down the machine and start over.

Any ideas out there? This is not an electrical problem since I get a bumpy ride with the motors hanging.

Any ideas at all would be appreciated.

[bill.young]

Hey Wes,

It sounds to me like your rails got mangled in shipping. They should be very straight and shouldn't have any bumps in them.

Have you contacted ShopBot?

Bill

[srwtlc]

Wes, one thing that can bow the rails in/out is if the legs themselves aren't square (meaning rail face to edge). If the face/edge that bolts to the crossmembers and rails is not square, when you tighten the crossmember bolts, it will bow the rail. Check all the legs and use the best (squarest) edge/face combo at each corner. I had one that bowed one rail enough that I couldn't position the v-rail properly. I had to shim between the rail and leg to get some of the bow out. I didn't want to take it down completely either!

[weslambe]

Bill, the bump is INSIDE of the channel where the t-nut is supposed to slide. This was a manufacturing flaw. There are no noticable bumps on the outside of the material.

Just went out and loosened up the supports that connect the sides under the table and moved the rails in so that I could put the BC rail into spec.

Cut some tests with mixed results.

Here's what I did and used:
Her-saf 90d Vee bit. (didn't change blade yet)
Columbo 5hp at 19000
1" per second straight line cut to 90" then moved over 1" and cut at 5" per second back to 0. Slow speed seemed ok with some very minor marks. 5" per second left noticable chatter marks.

Did a CP at 24,24
MS 4"
12" diameter.
Major chatter all the way around.

I turned off the controller then turned it back on. I had the sb3 running the whole time and it seemed ok. It lost connection when the controller was off but found it again as soon as I turned it on. I did a JH and the machine crashed into the prox at 22ips! Now I can't get the x to move in any direction except towards 0 no matter which arrow I push while in K mode.

I have rebooted everything and still can only move in one direction.

I trust Shopbot. That's why I bought them after my last fiasco with the other manufacturer's machine. I am certain that I will be up and running correctly soon, but I'm sure that I will need help figuring out what is wrong here.

Stan Holt has offered to send me his extra Porter Cable router to see if my Colombo is the problem. The help that most shopbotters give freely is greatly appreciated. The only thing that I need is a mounting bracket. Any out there for a loaner?

BTW, the reason that I am so anal about chatter is because of the cleanup time. Take a 60 door house and spend a minute on each door cleaning them up. That's one hour. Now spend 5 minutes on each one! Yesterday I spent from 3:30am to 9:30am sanding 46 doors to remove chatter. My wife asked if I had gotten any new business since I have my new machine. I told her that I didn't look since I was afraid that I might get the jobs and have to sand for 8 to 10 hours per day.

[srwtlc]

Wes, I have a new PC all mounted to a plate that was made to SB's specs If you want to give it a try. I recently put a 4hp HSD on and the PC is sitting on my tool chest. Or I could send you just the plate.

Did you manually pull the gantry out away from the prox switches. Try turning off the switches (VN). Are you using v3.5.3?

[weslambe]

Thanks Scott,

Stan's Porter Cable is on the way to me. I should have it by Thursday.

My Colombo is a holdover from my last machine. It has less than 150 or so hours on it and should be in great shape to cut doors. I did cut smooth square cornered doors on my last machine, but arches were garbage. That's why I got rid of it. Using a little logic, the Colombo should be ok since it cut good square doors.

Using troubleshooting skills tells me to eliminate the Colombo as an issue though. That's why I want to try the Porter Cable.

Scott, I may take you up on the mounting bracket. I would like for Shopbot to send me one as a loaner though. If it turns out that the Colombo is the problem I will simply buy the bracket and PC router and send the Colombo off for repair.

Jamie at SB helped me figure out why the motors only moved in one direction. Deleted ini file and all is well again.

Does anybody have issues with their spindle springs? My spindle drops slowly to the work surface when you turn the controller off. I have talked with tech support and they don't know why. Maybe new springs would help? (and my shopbot cap that I never got.)

[richards]

Wes,
There was an extended discussion of line and load reactors for spindles about a year ago. Eugene Watson added some valuable advice about Colombo/Delta VFD settings to minimize some of the problems. You'll find the thread here (http://www.talkshopbot.com/forum/show.cgi?tpc=27&post=33873#POST33873).

I have a line reactor, a load reactor, and an EMI filter on my 3hp Colombo; however, I'm using single-phase 240VAC power, so the VFD generates more electrical noise than a 3-phase unit.

So far, I have not seen a link between electrical noise and 'chatter'. In my case, the 'chatter' was totally solved with gearing. Since your PRS comes with gearing from the factory, I'm sure that Shopbot will have a quick fix or adjustment procedure that will get you running without 'chatter'.

[jsfrost]

Wes,
I am in the process of upgrading to a spindle, and SB tells me I need heavier springs. Did you get your PRS with the spindle verson of spring?

Jim

[weslambe]

Good news! I got my shopbot hat in the mail today...

... and Ryan at shopbot had me change the vfil settings on the driver controllers. It has helped. Could be headed in the right direction?

[richards]

Wes,
What setting on the Oriental Motor Alpha Stepper Motor Driver's V.FIL (Velocity Filter Adjustment Switch) is working best for you?

[Brady Watson]

Mike,
This (http://www.talkshopbot.com/forum/messages/26/21764.html?1181873956) was posted last week with illustration on setting the VFil. For those who have no idea what we are talking about, there is a velocity filter setting on Alpha motor driver electronics that will substantially smooth out the motors on your tool. 4G PRT/PRS tools also have this setting on each Gecko drive. Carefully turn the white screw on the Gecko all the way to the left. It may already be set from SB. On the Alphas, the '8' setting seems to be the max you should turn it before you get into diminishing return.

-B

[richards]

Brady,
Thanks. I noticed your post last week. When I saw that Wes was tweaking the V.FIL setting, I assumed that he had also seen your post. So, basically, I began to wonder whether the V.FIL setting is unique to each machine/axis/stepper (because of the load on that particular motor) or whether a universal setting will work for everyone

[Brady Watson]

Mike,
I've adjusted several Alphas using the '8' setting and all of them seemed to be fine. As far as extensive 'scientific' testing goes, can't help you out on that one. I do know that Ted mentioned that there was no advantage after the 8 setting when I 1st did it on my PRS setup last year. The reduction in motor resonance is amazing.

-B

[weslambe]

I have mine set at 8 and I get funny noises in the corners. Tz-tz-tz-tz-tz as it goes around the corner. I am using 1/4" downspiral bits at 20k rpm 10 ips (never getting up to speed on 5" squares).

I have another Shopbotter coming to help me out tomorrow.

I hope that I am not being too anal on this, but I do expect the best soon.

[richards]

Wes,
Brady posted some information on adjusting the Slow Corner Speed here (http://www.talkshopbot.com/forum/show.cgi?tpc=26&post=45513#POST45513).

When I make the 3-axis cut to sharpen the corners on a door there is a distinct change in the sound of the cut. When I used the values that Brady posted it helped. Also, the technique that PartWizard uses to cut rectanges gives smoother sounding operation at the beginning and ending of each line segment. (I don't use PartWizard or that particular technique when I cut doors. I'm just passing on the information for your perusal.)