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View Full Version : The New Bligeport - Second Installment



John Stevenson
05-20-2013, 05:36 PM
For many years I had a Hoffman dividing head fitted to the original POS and powered by a big stepper and a Division-master, nice bit of kit and in use most weeks doing things like splined shafts and keyways at 90 degrees.

Biggest problem with it was when i converted it from dividing plates and quadrant to stepper drive i used what I had.

http://www.stevenson-engineers.co.uk/files/hoffman1.jpg

This is it mounted on the CNC mill and I used the completer motor, end and coupling off a spare drive I had for the CNC. Easy job to fit if a bit overkill.

Because of where the old POS used to sit and the new Bligeport [ ] sits that motor is a right pain in the arse, or ribs if you are facing the right way.

For ages I said I was going to mount a smaller motor on top and belt drive it down, so Friday and today got it sorted.

http://www.stevenson-engineers.co.uk/files/hoffman2.jpg

New plate made and slotted for adjustment and pulleys fitted, wired up and tested and works fine. Just need a guard to stop chippings and fingers getting in the belt.

Soooooooooooooooo drop some 3mm MDF on the laser cutter [ because I had loads ] knock a load of layers off and a cover plate, ignore the blue, that's just tape to stop it overburning the MDF when engraving.

http://www.stevenson-engineers.co.uk/files/hoffman3.jpg

Drop of PVA white snot and jobs a good un.

http://www.stevenson-engineers.co.uk/files/hoffman4.jpg

PS Instalment 1.5 in that last shot. I fitted the carriage hand wheel off the scrap CVA lathe instead of the lever feed. Even though I have the quick release lever this is far better as you never have to position it

mike4
05-20-2013, 09:02 PM
Sir John ,

What size stepper did you use ?
I have seen quite a few advertised on various site lately with controllers , thought it may be time to have a play.

The prices of a lot of this equipment have dropped lately , even the multi axis controllers and Mach3 handsets.

Michael

Bgmnn1
05-20-2013, 10:49 PM
Barely knowing the difference between a stepper and servo, could they be viewed as incremental (stepper) and absolute (servo).

I have read servos are used for a more precise movement.

Are high count steppers just as good as servos?.

MetalMunger
05-21-2013, 12:17 AM
Sir John, retired must have a different meaning on your side of the pond.;)

macona
05-21-2013, 02:01 AM
Barely knowing the difference between a stepper and servo, could they be viewed as incremental (stepper) and absolute (servo).

I have read servos are used for a more precise movement.

Are high count steppers just as good as servos?.

Not really. Read this post I wrote a while back, it will probably answer your questions without derailing this thread:

http://bbs.homeshopmachinist.net/threads/52162-Buying-and-Using-Servos

DFMiller
05-21-2013, 09:11 AM
Nice job John.
What finish are you putting on the belt cover? Or are you going to put a oil finish on it? ;-)

In picture 2 you have a tool with red handles. What are they cutters? Details? Are they any good?
Thanks
Dave

John Stevenson
05-21-2013, 02:56 PM
Dave, I was going to spray it with a rattle can but might try oil first.
The red tool is a combined small wire cutter and stripper, obviously cutter at the top and the stripper in inbetween the handles at the bottom.

No setting or adjustment, they are spring loaded but just seem to work. After a while they do play up and not strip but when they get too bad >5 tries I just dump them and get a new pair out. They come from the shows on a cheap tool stand, I think they are about 3 each or 4 for 10.


Mike, that stepper is a size 34 rated at 495 oz/in which is more than enough, that big massive old generation type 42 motor is 900oz/in
Seeing as these drive thru a 40:1 reduction the torque is enormous and in my case it's only for positioning.

DFMiller
05-21-2013, 03:48 PM
Thanks John,
I will look at the cutters.
Have a great day.
Dave