PM1022V Spindle Bore

neodem

neodem

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So I just took possession of a new PM1022 and I bought I long drill rod (1" OD) to use to test the alignment and even though the PM has an advertised bore of 1" I found that I couldn't pass the rod through the bore. It ended up getting stuck about 1/2 way through.

Apparently it's not exactly 1" but a fraction less. The PM support person suggested that I could use a boring bar to open it up a little bit. Has anyone done this before?
 
Hi Neodem,

Probably a nominal figure. You could take a boring bar to it and open it out, but I wouldn't. Also it could be that the bore is actually 25 mm, which it probably is if its a metric lathe. In which case its the nearest conversion value to inch.
 
Just curious why you would advise against opening the bore. Is it because I could damage something easily? I would imagine I would only need to take off .001 or so..
 
Hi Neodem,

Chatter ! The only good way to open that bore a few thou would be to take the spindle out and either line bore it and hope you get a good finish or have it ground. Its just not worth it !
 
+1 to Mikey - also, is your bar perfectly straight?
 
Use a brake cylinder hone. It will take some time to do the job, at the same time it will smooth/polish the surface!
 
Be aware, some commercial drill rod is centerless ground. I've found that I can turn (skin cut) drillrod and leave lands uncut while taking off .0005 to .001 on the in-between lands. Thinking about this, it was on my Clausing/Atlas MK2. Can't believe I did work this accurately.
 
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