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View Full Version : Caution to everyone to pay attention!



Mike58
03-26-2015, 09:46 AM
I just last week converted my QC chuck to the carvetight chuck. New bits and had some problems with some other things that it seems the A907 kit and new chuck appear to have cured. So, I was able to salvage a in process carving that had already gone 2 hours when the machine had stopped. Machine carving time was 7 hours and 47 minutes on my brand new carving bit and carvetight chuck.

I also would like to point out I can tell a big difference in the vibration now when the machine is carving from before changing the QC chuck. I expect this to produce better, smoother carvings due to the reduced vibration also.

I had noticed when the carriage was moving over to the bit plate to find the bit that the bit was going up and down 2-3 times and the tip seemed to no longer be touching the bit plate but now against the side of the bit. This all began after replacing new hardware on the machine, so I sort of thought it was suppose to do this now. Next project was a ribbon pattern I purchased from the pattern depot on mdf. About an hour carving time. The bits where put in like always and again the carving bit goes down by the bit plate and touched the side of the bit. Seems everything is good - carving pattern. I walked back into shop (carving machine on porch outside) and as the carving machine starts carving it sound different. Like something isn't right - different; so I hurried back outside to see the carving bit buried in the 1/2" thick mdf to within 1/4" - 3/8" of the adapter and the mdf is not cutting but being peeled over by the bit were the cutting flutes stop. Crap!

Stopped the machine, and trying to see what happened and why. Turns out (thank you for all the online troubleshooting and tutorials) that the bit plate was sticking enough that the plate wasn't rotating out fully to get under the bit. The bit was probably going 3/4" below the tip touching the bit plate when the side of the bit would contact the bit plate. So it seems the machine thought the bit was about 3/4" shorter than it was - which caused the bit to probably go full depth down to carve.

Lubed the bit plate pivot and although I couldn't really tell it was any better it did rotate under the bit properly. So the carve was done after flipping the mdf as the original attempt resulted in a gash cut throught the mdf instead of a .25" carve region as intended. The flat areas look good, the edges of the ribbon that are proud of the .25" carved region are all ragged and rough looking. Actually seems to show this in the pattern itself - but will have to rerun it with a good bit to see.

After finishing the carve and cleaning the machine, I happened to notice the metal rod that runs across the machine below the belts has a gash in it. That was because the carving bit was hitting it I discovered.

75174 The bottom bit is a new one that arrived yesterday, the top one gave one good carving out before the tip was ran down into the metal rod below where the bit transverses. The blue discoloration is from the bit being that deep into the mdf - above the cutting flutes, and the tip is also damaged from hitting the steel rod. So this was an expensive mistake due to ignorance on my part that the bit plate didn't fully rotate under the bit. Had this happened before changing the z motor and replacing the QC chuck with the carvetight I might have suspected something out of the ordinary.
I thought this MIGHT save someone else a $40+ bit. You should be standing at the machine during all of this to make sure everything functions correctly before the carve starts. I did see it didn't function as it previously did before changing out hardware, but thought this was now how it worked, which proved to be incorrect!

lynnfrwd
03-26-2015, 10:01 AM
Yes, ALWAYS watch to make sure the bit ACTUALLY touches the bit plate.

Good reminder.

bergerud
03-26-2015, 10:26 AM
While it is certainly good advice to always watch the bit touch the bit plate, I do not think that a poor touch at the bit plate explains the dive your bit took. The depth is determined by the touch on the board, not the touch at the bit plate. A poor touch at the bit plate should only confuse the firmware and after the board touch result in a reload bit message. You may have two different problems here. Keep your eyes on it.

Mugsowner
03-26-2015, 06:32 PM
As far as the bit plate sticking, I always listen for the plate to slap back to its normal position. If I do not hear the slap, I know that I must clean and lube the spring and pivot point.

Digitalwoodshop
03-26-2015, 06:43 PM
2 bit plate touches GOOD.... 3 bit plate touches.... BAD....

Always stop the machine and investigate the Z if you get 3 touches. If the machine did 3 touches than #2 was not the same as #1 but #3 was ?? don't know.. likely same as #2... But the point is something is WRONG... Dirty Rails, Dirty or dragging Z Roller Rail Bearings, Dirty Z Belt Cogs, BAD FFC Cable, Dirty Encoder, LOOSE Encoder clear disk, LOOSE BIT, LOOSE Z Roller Rail Bearing SCREW... just to name a few...

With 3 touches the machine will work BUT comma.... It may not cut what you expect...


AL