2016 POTD Thread Archive

[Bill W.]

Bill,

Are you using 7018AC? I use an old AC welder routinely with 7018AC and the ground is hooked to the ground side.
I will have to try this and see if there is any difference. Have you tried it both ways and there is a difference?
Just curious I guess. Thanks.

Cathead.... no, I used just regular 7018 that I had left over from a repair job using a Miller Big 40. Honestly didn't know there was a 7018AC.

 

[cathead]

Cathead.... no, I used just regular 7018 that I had left over from a repair job using a Miller Big 40. Honestly didn't know there was a 7018AC.

Bill, That's interesting. Have you tried both polarities with different results?

 

[British Steel]

I would love to save it, it's probably between 100 and 200 years old but it came to me in a bad way from someone who got it when it was in a bad way.

Thinking about it, theirs a good chance it's forged steel.

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Stuart

That looks a perfect candidate for electrolysis, you'd probably find after a few days in the tank bubbling and frothing it was back in working order, just needed a spot of oil - I had a big drill chuck that looked like a rock it was so rusted, after a week in the tank I took it out and everything moved and spun as it should, looked pitted but otherwise pretty functional!
Electrolysis is weapon of choice for museum workers etc. trying to reclaim old iron tools etc. as it lifts the rust without affecting the sound metal underneath, if it's good enough for "conservation" it's good enough for me

Dave H. (the other one)

 

[RJSakowski]

I would love to save it, it's probably between 100 and 200 years old but it came to me in a bad way from someone who got it when it was in a bad way.

Thinking about it, theirs a good chance it's forged steel.

View media item 95249
Stuart

Most of those old leg vises were wrought iron. I have several and all mine are. IMO, it's worth more as a vise than as machining stock.

Wrought iron has some properties that make it less than ideal for machining and for projects. It has a multitude of slag inclusions which will do a number on HSS tooling and the nature of the beast is such that it can rip out a chunk from a hole drilled close to the end of a bar, much like wood when drilling close to the end. Best engineering practices would wrap a bar to form a loop and forge weld the end of the loop to the main bar. Years ago, I disassembled a bridge built in 1893 and much of the iron was wrought. The tie rods to 2" diameter bolts were all forge welded loops. including the 3/8" x 2" flat stock which was looped and welded in the flat dimension. The smoking gun on these rods was the teardrop shaped bolt holes.

 

[chevydyl]

I turned my mill into a cnc lathe, I had some issues with CAM but using the mach3 turn wizards I was able to get this sphere turned sucessfully, if you would like to see a video about it, check out my YouTube channel, I also released part 3 of the cast iron square series. If you would like to see an epic crash, watch the video.....
Here's a link

Hmm I'm having trouble uploading the photo, I'll have to come back to this on a computer and post it

 

[FOMOGO]

Pretty cool. If at first you don't succeed, and all that. Let us know where you found the issue when you figure it out. Mike

 

[chevydyl]

I think I know what it is, I changed the routing of the power cord for the computer, so it may be causing an interference with that drive, I have had this issue in the past but never as bad as this where it took 5 runs to get a part done. Before I tried this, it ran for probably 50 hrs or more without issue. Another thought is now the mills motor is closer to the X or Z axis servo and encoder, which could be causing an interference as well.

BUT, as far as I'm concerned it shouldn't be a problem, I'm using high quality Allen Bradley servos and drives, like $7500 in components when new

 

[chevydyl]

heres an action shot

 

[JimDawson]

I think I know what it is, I changed the routing of the power cord for the computer, so it may be causing an interference with that drive, I have had this issue in the past but never as bad as this where it took 5 runs to get a part done. Before I tried this, it ran for probably 50 hrs or more without issue. Another thought is now the mills motor is closer to the X or Z axis servo and encoder, which could be causing an interference as well.

BUT, as far as I'm concerned it shouldn't be a problem, I'm using high quality Allen Bradley servos and drives, like $7500 in components when new

It could be an intermittent power problem on your encoder or resolver supply. These are a real PITA to track down, best done with a scope.

It sounds like you need to program in an ''encoder fail'' function. This is where if the encoder error becomes too great, the machine shuts down. In the case of my machine, if the encoder error is >500 (0.020 inches) in any axis, it triggers the error routine, and cuts power to the drive enable signal on all axis.

 

[chevydyl]

would you do that in mach3 or in the drive software? mach3 as you probably know doesn't support positional feedback, or closed loop operation. ill check what the error is a little later and post back about it, but its the same reoccurring error, and sometime it will switch between drives, x then y. currently cnc4pc who makes my breakout board doesn't support receiving an error signal from Allen Bradley drives, they were supposed to work on making a board that would do the trick, that would certainly help with keeping crashes from happening.