2016 POTD Thread Archive

[JimDawson]

I think you would have to do that in the drive software in your case. I have only worked with one A/B drive so I'm not up to speed on what it is capable of. You might be able to program the output relay on each drive to close (or open) on error. Those wired in series with all of the enable signals should provide encoder error protection. That way an error in any drive would kill the enable signal to all of the drives.

 

[chevydyl]

well....lol I have my enable to the drives hooked to a switch, and programmed in the drive to be Enable/Reset, I have some work to do for sure on the system..... I would love for it to be more integrated

 

[JimDawson]

Might be time to start thinking about a more sophisticated motion controller board

 

[stupoty]

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)

Ahhh ok ok, i will go and do some electrolysy research

Maybe I will just oil it and make wall art from it if it doesn't cleen up.

Stuart

 

[chevydyl]

I suppose, the major issue I that the Allen Bradley uses 24v for almost everything, the board I got is the 24v board from cnc4pc, but some of the signals are still 5v, like the enable and servo error signals.... I was looking at some boards yesterday, but its not in the cards to spend that kind of money, it works at the moment, and if I spend any more money on the machine it will be for another drive and servo for the 3rd axis.
I have already downloaded Ubuntu, I was thinking of trying out LinuxCNC, I hear great things about it.

 

[Bill W.]

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

Cathead, I didn't try the 7018 on the buzz box before I switched it. It' not that hard to do. One of these days I'll switch it back and give it a shot.
Bill

 

[T Bredehoft]

My boss, (eldest son) who runs the model airplane business has got it into his head that he needs to have to sell torque meters for the rubber band motors of planes. They wind up the rubber bands until they are just-so tight, and let them go. It seems consistency is desired between flights, or needed so they know how long the flight will be, or some such. He came up with an idea, showed me one he had purchased used, and let me go. After a day of drafting pictures, and two days of playing in the shop, here's the result.



The right end (dummy shaft at present) is attached to the winder, the rubber band is attached (needs thread at present) at the left end. As the winder is turned, the rubber band tightens, moving the pointer counter clockwise around the body. If I got the spring right (a coil spring (.055 music wire 8.25 inches long wrapped around a 3/4" mandrill). attached to the body at the right end and to the output shaft on the left. The pointer will register inch ounces of torque, up to 120, on the strip of paper. Inside are two Oilite bushings and a thrust bearing to reduce friction. As you see it, it's 4" long, 1.5" the largest diameter. It weights 145 grams.

 

[Mark_f]

A friend of mine has a Rockwell 11" lathe. The cross feed nut is worn out and a new one can't be found. I never cut an acme thread before , but what the heck, how much harder can it be? .....yea .. right . I milled a block out of a round piece of bearing bronze I had lying around. The screw is 1/2-10 left hand acme. I drilled a .375 hole for the minor diameter and then proceeded to try and make a threading tool since they are $100 on eBay for an acme boring bar!!!!!! Spent two hours grinding a nice tool on a 3/16 HSS bit and could not get it to silver solder on the end of a bar. I ended up with a mess.. I got a piece of 3/8 HSS lathe bit and hogged a tool out of it. Took a couple hours. It is ugly but the business end is right and that is what matters.
View attachment 126687 View attachment 126688
These are pics of the bit. Told you it was ugly.

View attachment 126686 This is the finished nut block. This is at least a class 3 fit . I can turn it with my fingers but it is stiff. I left it that way because this is a new piece of acme screw and I'm sure his is worn in the middle. I am hoping this will reduce the backlash from screw wear. I left the nut in the lathe until I try his screw in it , just in case I have to take another cut in it. Now I have to try to figure out the height of the nut to fit in the saddle and line up with the screw. I don't yet know how I will determine that. If I cut too much it will require shims to make it work. From start to finish this project has taken all day to get to this point.

I finished the lathe repair for my friend Mike.
This is the finished nut. It was difficult to determine the distance from the screw to the top of the nut,( but I found a sneaky way to do it).
This is his finished saddle waiting for him to pick it up. The nut fit sow well, the screw turns smoothly and with a .001" indicator on it , I cannot measure any backlash. Now , I know I can do it, I am going to make all new nuts for my mill as they are pretty bad.

 

[David S]

Nice going Mark. I have done single point threading, but don't recall doing internal..and obviously not ACME. If I ever have to do it your post will help me.

Thank you

David

 

[Mark_f]

Nice going Mark. I have done single point threading, but don't recall doing internal..and obviously not ACME. If I ever have to do it your post will help me.

Thank you

David

Acme is just as easy as a regular 60° thread. there are just a few things to know.
P= pitch of the thread
D= depth of the thread

D= 1/2 P + .010
Minor diameter = Major diameter - P + .020
Set the compound at 14 1/2°

Nothing to it. but it is nice to have a screw to fit it to.

I thought it was some big secret to do doing acme threads until I finally tried it. nuthin to it