Intermittent problems

[pqkenai]

Anyone got any ideas on the causes of the following?:
[1] Halfway through a project, the head comes to a halt, always raised,with the bit still spinning. Once, pushing stop & enter got it going again, but usually it takes no notice, just remains stationery with the cut motor still going.
[2] X-axis belts coming up to speed slowly when measuring the board.
[3] During board measuring, part-way along, x-axis begins alternating direction, faster & faster.
[4] An occasional deep hole in raster mode - a single plunge by the 1/16 bit.

[bergerud]

[1],[2],and [3] are symptoms of brass roller and x motor encoder disagreement. [1] for example: if the x axis increments for the next raster line and the brass roller does not register the move, the head stays up with the motor spinning. It is"waiting" for the brass roller to register the board advance. (Try giving it a push!)

I would say that you have a problem with either the brass roller or the x drive system. The brass roller encoder could be full of dust or the roller is being interfered with somehow. The x drive system could have too much backlash. I have heard x gear backlash stated as the reasons for [2] and [3].

[Digitalwoodshop]

Very strange... I half wonder if the head pausing and going up still running is somehow related to the machine not being happy with the X Brass roller position... and pausing confused?

What belts do you have? Sand Paper Belts then I would look for a rolled under belt at the brass roller.... VERY hard to see and 9 times out of 10 when I suggested this in the past, got a reply... NOT rolled under... and a few later wrote... OK.. I took the belt out and yes is was rolled under.... Rolled belts 1. cause friction and make the drive work harder and drag in start up... and 2. The rolled under belt raises the board off the brass roller.

Rubber Belts... Sometimes like a radial tire squatting, when you crank down on the board the belts squat and bulge and touch the brass roller is not centered. Some have had to make the mounting holes oval for the brass roller.

Head Pressure, Humidity? I have had to un crank the pressure slightly as the board was measuring in the morning when the machine was damp from humidity and the under side of the belt was STICKING to the bottom tray as it moved. Sometimes I would let the machine measure the board twice to help dry it out.

Excess Dirty Belts.... as in the underside.... Sawdust and pine pitch causing sticking of the belts... un likely but worth a mention...

What software are you running?

AL

[lynnfrwd]

Anyone got any ideas on the causes of the following?:
[1] Halfway through a project, the head comes to a halt, always raised,with the bit still spinning. Once, pushing stop & enter got it going again, but usually it takes no notice, just remains stationery with the cut motor still going.
[2] X-axis belts coming up to speed slowly when measuring the board.
[3] During board measuring, part-way along, x-axis begins alternating direction, faster & faster.
[4] An occasional deep hole in raster mode - a single plunge by the 1/16 bit.

I'm wondering if this might be the cause of your x-axis problems:

Improve board feeding

I have found that the two guide plates that the board moves between are too low, & the board sometimes rides over them. Here is an easy fix: for the non-moveable one, grasp each end with a pair of pliers & bend it upwards slightly, so it rides higher up the side of the board. For the moveable one, remove it from the machine [undo the two screws on top of it at its centre & then slide it away from the keypad side till it gets past the side of the drive belts & then lift it upwards]. A tab is bent inward on each end of it, which slides along the machine chassis. Use the pliers to straighten it a bit, then replace the guide & it also will ride higher up the side of the board.

[bergerud]

I think Connie is onto something here. Pqkenai, is the brass roller proud of the plane of the belts? It should be up around 1/8" so that the board presses it down.

I am thinking that the belt assembly may not be bolted down properly. Maybe a foreign object between the belt assembly and the base of the machine.

[bergerud]

Maybe you have rubber belts and no spacer washers under the squaring plate?

[cestout]

If you have a bunch of hours on it, maybe the O ring needs to be replaced.
Clint

[DocWheeler]

Or the little piece of rubber tubing under the brass roller is misplaced.

[pqkenai]

Well, there's plenty to try there! I'll get back to you. Thanks.

[pqkenai]

OK, I'm back! I have rubber belts. The encoder cover was clean inside. Haven't checked backlash, but only 175 hours on the machine. The brass roller almost touches the belt when a board is loaded. It can't be adjusted, can it, unless the holes are modified, which is a finicky job, since there are 4 of them & they are small & very close together? Software is Designer 1.187. I doubt that sticking belts is an issue, as it is fairly rare, & seems to repeat on the same board, so the board itself seems to have something to do with it. Connie, what might that previous post you quoted have to do with it? Where is the squaring plate? The O-ring looks fine. Where is the little piece of rubber tubing under the brass roller?