Need Help!- BP series 1 loosing steps

[bartL]

Hello,
I've a series 1 cnc mill retrofitted to mach3 and I'm very satisfied with it.
But when I did some real heavy milling in aluminium yesterday my X-axis couldn't handle it while my Y and Z seems to have no problems with it. What can be wrong? Why seems my X-axis much weaker then the others?

Thanks,
Bart

[kewl_cat]

I had that problem once and it was the key had sheared on the shaft where it attached to the table. The nut was still tight and it would only lose a few thousanths per pass under heavy cutting.

[bartL]

kewl_cat,
Thanks for your respons.
I think we're not talking about the same problem.
Last time when I had this problem, I did some heavy cutting in aluminium, I was milling a circular pocket. But when it probably became to heavy the X-axis totally stopped moving and you could see I was trying to move but it couldn't. In the mean time the Y-axis was still going on without any problems. So my circular movement became a lineair movement in Y direction.
Hope you understand what I mean.
In my opinion X and Y should have the same strenght for movements but at my machine it seems they don't.

Thanks,
Bart

[VWSatOz]

Maybe you need to replace all the transistors in the x axis drive. &/OR the motor may have been pulled apart & lost some of its magnetism

[bartL]

Well,
I've checked all transistors a few months ago before I started retrofitting the machine and they were all good. I don't know what the problem could be with the motor, it's very accurate when I do rapid moves or easy cutting. But heavy milling (15mm deep with 25mm raw end mill) seems to be a problem.

Thanks,

Bart

[VWSatOz]

Just because its alum doesnt mean you dont need lots of grunt to cut it. I assume your machine still has the original stepper motors which have only a limited amount of feed force & no feedback to stop the machine if you overdo it and get the slip etc. A 15mm deep cut with a 25mm diam cutter might be a big ask if its a full width cut. If you can climb mill with prox 2/3 width of cutter using at least 3flute mill the cutter will not need as much feed force as it pulls itself into the material. Might be best just to establish what is the safe max depth & width of cuts you can take & be content with that.
Its many years since I had my Bridgeport CNC but I seem to remember it went great using 16mm cobalt unimill (3flutes) with about 12mm deep cuts in mild steel or tool steel with feed of about .07/tooth.
The standard pocket cycle might not allow less than full width of cut in the area where it steps out for the next bigger circular path but at least you can nominate a stepover of less than full diameter.

[VWSatOz]

Maybe check the transistors again. Mine seemed to pack up after 1 year & you must replace all four as a new set, not just an odd one that fails. This was always my biggest problem... final drive transistors!

[bartL]

I know it's a big ask for the machine, but why doesn't the Y-axis hasn't got any problems with it? I was cutting full witdh with a 5 flute roughing and mill. It's hard for the machine but it seems like that's not the problem. When I'm moving the machine in rapid the sound of the Y always sounds different then the X. Maybe the transistors are the problem but no one was shorted last time I checked them and the difference in sound while moving is nothing new.

Thanks for your help!

Bart

[VWSatOz]

Can you do a board swap? I cant remember what it all looks like but is you can use the X stuff to drive the Ymotor & you find then that the Y axis has the problem then at least you know where the problem is! This method might also be used in other prior control board areas prior to the final drive. The Y axis has a much larger total mass to move & may abosrb vibrations better than the lighter X axis, but this is a long shot. The sound should be the same on both drives if all the bearings races &ballscrews are OK. Any sort of growl points to some electronic problem I would think.

[bartL]

During the retrofit I already swapped the boards because I had another problem which had to be solved. At that time I already figured the difference in sound stays on the axis, so it's not a problem on the board. But maybe there's another electrical problem.

Bart

[craig96us]

Check to make sure you are getting way lube to your X axis. Lack of lube to the ways will create the problem you described.

[VWSatOz]

I have heard that you should NEVER pull apart a stepper motor as this will cause a weakening of the magnetism in the permanent magnets. I guess the armature acts as a "keeper" & if you pull it out the stator magnets lose some grunt as the poles are too close togehter sideways. The reassembled motor will still work but not have same output, maybe only 50% of torque. If you can get a new motor, or have it remagnetised as an assembly (assume not easy), or test the residual drag of your Y &X magnetic resisting torque, you may find out if this is the cause of your Xaxis problem.