Motor revving

[First Sergeant]

So I recently burnt my flex shaft sheath while running a project. I had already carved three projects earlier for a total of 4 1/2 hours. During the fourth project I started hearing a rattling sound but it went away and then started back up and before I knew it I burned the outer layer. I called CarveWright and was told to ensure the flex shaft is seated correctly in the motor due to them being jarred during shipping. Mind you I already had 25 hours on the machine. I took out the flex shaft and reinserted it and noticed the retaining screw does not screw down to secure the flex shaft so it doesn't rotate out of position. I ran a test motor with my finger ready to hit stop in the event it began rattling again. No rattling as of right now. Now I realize that my motor sounds like it is revving. Has anyone had any familiar issues and any advice that can help me figure out these issues. During this time my top cover stoped engaging the motor side button causing me to have to push the cover down so the motor would run and have to cut more of my cover so it would engage better, again, never had this issue during 25 hours of carving, why all of a sudden now. Is this all connected or just coincidence? Three issues:
1. rattling flex shaft (possibly fixed but retaining screw does not engage flex shaft)
2. motor sounds as if it's revving in and out
3. Top cover stop engaging right side button for motor.

[bergerud]

Someone else was complaining about the cut motor revving up and down. I just ran the cut motor test on each of my machines and they both sounded the same. It does sound like they are revving up and down a little. They sound like they are trying to run flat out but there is an oscillation to it. Maybe some kind of phase shifting from the speed controller since the motor in not under load. I think it is normal. I do not think it indicates anything wrong.

[First Sergeant]

Bergerud,
Thank you. That is a relief. By any chance do you know if it's normal for the retaining screw that is screwed above the flex shaft, motor side, should continue to spin without fully tightening. My gut tells me it is stripped out. Seems to me the purpose of the screw is to prevent the flex shaft from rotating clockwise out of position and schools tight comety to prevent this from happening.

[bergerud]

It sounds like the screw is striped. It is supposed tighten against the sheath to stop the sheath from twisting. Maybe try a slightly bigger screw? (I think I would tap the hole for a bigger screw.) Or somehow haywire the sheath so it cannot twist and come out.

[fwharris]

I also think it is normal for the cut motor to change speeds during the test. Not sure if it is programed that way to check the rpm circuit or like what Dan said.

For the set screw being stripped out I would also go with taping it for a slightly larger screw. I would not suggest going very big as you might risk cracking the case. I really do not think the set screw is to hold the sheath in by pressure but is more of a stop. When I install the sheath into the motor I always rotate the ears of the sheath end so that they go into the slot inside the motor case.

Your cover switch issue, It might be possible that the hinges for clear cover have gotten out of alignment. If you have had the top off and clear cover has flopped open it can force the switches loose.