I'm sure someone has had the same problems as me, so i was hoping someone could give me some insight....

We are making some parts out of ground bar stock that the customer supplied, and it's already ground to the size they want on the OD. However, my citizen b12 keeps scratching up their stock (they want to keep the 16 finish....). we got a special guide bushing that supposedly is soft enough to keep from scratching up the 303, but i haven't noticed an appreciable difference. I've loosened up the GB enough that the stock slides out during re-chucking and makes the part too long, and there are still scratches :confused: :angry:

Is there any tricks anyone uses to keep the OD looking nice and pretty?? I thought about making my own guide bushing out of brass or bronze, but that's a bit of a project, and i'm busy enough. I know i could always get stock a bit bigger and just turn it down (I'd RATHER do it this way, actually), but is there any way to use the customer's material??
thanks!!

PoiToi,

I sometimes have to use stock finish on parts where scratches are not acceptable. What I do on occasion is to take a few pieces of the material being turned and heat treat them as hard as possible (if you have heat treating capabilities). I then put the bushing in the machine and leave it just slightly loose on the material, so that the bar will slide through fairly easily. I then take my hardened pieces and apply some VERY fine lapping compound to them. I proceed to push a piece with the compound through the bushing for a while. I then tighten the bushing up to almost where you would run it at during operation and run another compound coated piece through it. What this will do is ensure that your bushing is truly sized to your material. This usually takes care of all my bushing issues. Good luck!

We also Run into this reguarly ..Lapping the Bushing as Yoopertool said, will ussually take care of it...Breaking the Slot edges on th Bushing Before Lapping can help as well..As small diamond file usually works if the bushing is big enough..

get a non slotted gb, non adjustable, but much less scratching.. also if you are picking this off the sub may be your problem, or the main for that matter