Cut Motor won't start after bit change, RPM issue, and more...

[liebhaber]

Issue 1: When running the motor will start to speed up and slow down. It's not the 1st gear/2nd gear, it is a very noticeable slow down and then speed up randomly. It has created some issues with the quality of the carving because some areas of the wood are not cleanly cut when it slows down. The slow down, speed up occurs after the motor has been running for a while (anywhere from 30 min to 1 hr). It is noticeable with the carving/cutting bits and extreme with the 60-V bit used in the last carve.

Issue 2: The motor will not turn back on after a bit change. Just broke a second bit this way because I couldn't catch it fast enough. There is a noticeable "clunk" noise like the motor wants to start, but it does not start. The machine doesn't know the difference and behaves like it is starting to carve (hence the broken bit when not caught fast enough). When doing a cut motor test, the motor will either make the "clunk" like it is trying to start but doesn't, or else it will be completely silent.

Issue 3: No matter what I do, the board will always measure .75 to 1 inch shorter than it is. I have put masking tape along the roller edge, I have checked the board sensor, ensured the sandpaper belts are not rolled up (thanks Al, I actually trimmed them as you mentioned in one of your posts). No matter what, every board measures short.

I purchased this A model machine with 12 hours on the motor in early December and have done the following:

When new, a power fluctuation error was fixed by cleaning out the machine, has not returned. The motor housing completely shattered on carve #2 where the flex shaft sheath attaches. I ordered a new housing and replaced it. Needless to say with that operation I have checked the cut motor brushes and they are fine, barely worn at all. I removed, tightened, inspected, and re-installed all of the motor cover switch connections. Everything inside the motor looks fine, no damage that I can see. Installed the DIY carvetight upgrade.

If I remove the cut motor, tear it apart, check connections, and put it back together (no joke I don't do anything else to it), it will come back to life and run until the next bit change, at that point it is completely dead again.

Both before and after the CT upgrade the quality has been terrible, I don't know if this is an RPM issue or not, but many tear-out issues where patterns will be chipped or non-symmetrical. Also had a cut-out that was skewed. One outside half was perfectly straight, the other outside half had a 10-15 degree "stair-step" feather to it.

I am ok with doing user maintenance but I don't want to replace the whole machine in parts already. I've already put $300 into upgrades and misc parts so far. I may just sell it unless there is an inexpensive fix.

I have attached both the latest carved MPC so you can inspect if I'm doing something to cause the RPM issue (demo items), and the MPC which was "skewed" (hesse sign).

[chief2007]

I would pull the motor - open it up clean blow out any dust and then look for a loose or burnt wire. I had a similar problem occur with one of my machines low hours and cut motor stopped. Was a combination of sawdust and a burnt wire in the motor. clean the motor and solder the wire - 400 plus hours later and still running well - of course I have changed the brushes twice.

Could be the circuit board the reads the magnetic to determine the RPM on the top of the cut motor or the X termination board as well.

[liebhaber]

Did that already. I have had the motor apart about 10 times in the last week. Everything looks a-ok.

[bergerud]

I would connect the motor directly to AC independent of the machine. If you are right, it will spin up to 20,000 rpm like any router motor. Having eliminated the motor as the problem, next would be the X termination board which controls the motor.

As for the board measurment error, that could just be a calibration prolem. (Is there a too fat O ring on the brass? Do you see brass roller tracks on the board?)

[liebhaber]

I am not quite savvy enough to hook the motor up directly, any pointers on that?

[liebhaber]

I should also note that the board measurement problems appear to be on the left end of the board, right end seems to measure ok. When the left end gets measured, it seems to be measured 2-3 times in different locations as if it's trying to find the edge. The right end just gets measured once. Carving all poplar and pine, nothing dark colored and all board sensor readings are over 100.

[Digitalwoodshop]

Lots of great information.....

Lets start with length measuring problem first....

I know you checked the sand paper belt for roll over.... but I would rip a 1/2 inch section from the belt at the brass roller, the one under the cut motor... Also blow air around the brass roller so no sawdust impedes it pressing up to the underside of the board.

Cut Motor... Since this is a on going problem and the Cut Motor has been taken apart a few times and no problems found... I would RE Crimp the push on connectors, I have heard of them needing to be re crimped.

Watch for a loose right cover switch or loose screws for the clear cover.

Next take a close look at the C1 Cap on the X Termination board for one end broken off....

Let us know,

AL

[bergerud]

When I connected my motor, I just used an old lamp cord and pushed the two wires into the motor connectors. It does not matter which wire is which. Tape them so they do not come out and plug it in. (If the motor is not attached to the machine, it will give a pretty good torque jerk, so hold on.)

[SteveNelson46]

liebhaber

A bad power supply has been known to cause most if not all of the problems you are experiencing. Especially in "A" machines. If you can, swap it out with a known good one. This may or may not fix it but, you might want to keep it in mind.

[liebhaber]

Al, I did the belt tear off as soon as I saw your post about it when searching. I have also done nearly everything I can think of to blow out/ brush out the brass roller area.

I spent about an hour yesterday inspecting the right cover switch and all of its connections. That was my first thought, but the motor always seems to want to start. At least that's what I think the clunk noise is.

Do you have one of your many pictures or a link to the c1 cap? Thanks!

[cestout]

I just had to "recrimp" one of the connectors from the cover switch after I repaired the motor. I was putting the reopaired motor in the newer C machine.
Clint

[Digitalwoodshop]

That CLUNK when you close the cover is normal at least on my machine...

Here is the C1 Cap.

AL

[liebhaber]

I'm a little under the weather today so tomorrow I will try some of these fixes.

Al, just to be sure we're talking about the same clunk, it sounds like the motor does maybe a 1/8 spin or less, like it is getting set or something, not the clunk of the cover coming down onto the machine.

Now that I think about it, the motor cover switch may be the culprit. I never get a check cut motor which I assume would happen with brushes/motor issues. The machine always acts like everything is running fine. That's how the bit broke, 1/8 cutting dove about .2 into the board without spinning, I just didn't catch it before the X axis moved and *snap*.

Did you need to strip and re-crimp and have a new adaptor, or did it just pull off and you re-insert/crimp the connection?

Also, how about the RPM fluctuation? With the 60-V bit it almost sounded like the motor spun down to less than half speed (by loudness). Then it sped up as the bit touched the board, and would slow down again at various points along the carve.

Thanks everyone. I'm trying to do what I can short of selling the machine since my wife noticed I spend more time trying to fix it than I do with her! :eek:

[liebhaber]

Well I only had a few minutes at lunch so I took a hunch and tapped on the cut motor to free up the brushes if they had gotten stuck in the sheath. The motor came back to life and surged for about 10 seconds before reaching what sounded like full RPM. I'm guessing when I had to pull and reinstall the copper sheathes for the brushes when changing the motor housing it changed the tolerances a little and the brushes are sticking.

I usually pull them out before pulling the motor apart so I probably didn't notice and when re-installing them was pushing them all the way to the proper location. The surging I'm guessing is a result of the brush backing off and not providing full force for the motor.

Any other ideas or does this sound possible?

THANKS! It's great to get so many responses.