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Adventures In Tramming My Pm935ts

Discussion in 'PRECISION-MATTHEWS' started by Jeb1234, May 12, 2016.

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  1. Jeb1234

    Jeb1234 United States Iron Registered Member

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    I got tired of fighting with my piece of junk milling vise and bought a Kurt D688 for my PM935TS, so I thought it would be a good time to tram the mill.

    It wasn't that far out, so I started with a Starrett Last Word indicator on an arm from the quill that read to +/-0.0005". It was acting a bit finicky, so I switched to a Brown and Sharpe which read to +/-0.00005".

    The thing that I noticed with the B&S indicator was that when I put pressure on the mill head, I could see the thing move. The indicator moved by about 0.0007" when the indicator was furthest from the mill on the Y-axis and about 0.0003" when it was at the shortest distance on the Y-axis. I was giving the milling head a pretty decent shake - maybe about 30 lbs or so. Is this normal? All the bolts and the gibs were tight on the head. I couldn't see anything that could move...can the cast iron really flex that much?

    Anyway, I was able to get the head square to 0.0002" over the depth of the table and mounted the Kurt vise. Squared it to within 0.0001" over its length and ran a test by surfacing the top and bottom of a 2x7" piece of Al and it measured within 0.0002" top to bottom/end to end so I was pretty happy...especially since I was lucky to get within 0.005" with the old junk vise I had.

    Also added a power feed on the X-axis and a DRO...I should have done that a couple of years ago. They're awesome.
     
    rdean and jeff_g1137 like this.
  2. tmarks11

    tmarks11 Active User Active Member

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    Nice work....but... with a bridgeport style mill, trying to tram less than 0.001" is wasting time. Deflection during cutting is going to cancel out your fine tuning anyhow. Call it quits once you get to 0.001", and spend the time you save cutting more.
     
  3. keenlyside

    keenlyside Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    My dad was (is retired) an Aerospace engineer and he drilled something into my head from an early age. "Everything Flexes" I keep this in mind when thinking about the OP question of does this much cast iron actually flex that much as it helps remind me that once I get my head around the idea that nothing is so stiff that it doesn't flex at all that it is easier to accept what you see on the dial gauge. If you saw 0.0007" with the 30lbs of push then that is almost certainly how much it flexed.

    Most of us have compound cross slide saws of one variety or another and cut to 1/16" or 1/32" of squareness all day long. Next time you use that tool put just a few ounces or so of side load on the blade (tool unplugged of course) and watch the blade move probably 1/8" or more. Does this really matter in practice, no because the wood doesn't put side load on the blade, but say your saw was out of level and the sliding assembly was loading the bearings to one side....

    Cheers

    John
     
  4. wrmiller

    wrmiller Chief Tinkerer H-M Supporter-Premium

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    Yep, everything flexes. Even cutters! To get as accurate dimensional results as I can I found that learning how the machine/cutter/material reacts to different speeds and feeds has been more productive for me. YMMV.

    Not sure why some folks 'chase zeros' like that, but hey, it's not like I never did it when I was first getting started. :rolleyes:

    Now when tramming my 935 I will take it down to somewhere between .001 and .0005 which is fairly quick and easy, and call it good.
     
  5. keenlyside

    keenlyside Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    Sage advice for sure.

    To be honest, I chase zeros as well. Mostly because I really like the idea that everything is perfectly aligned (no such thing but a nice ideal) more out of fascination with, and appreciation for, the machine than what that alignment actually means to the results of the machining process. I suppose it satisfies my CDO (OCD with the letters in the alphabetically correct order, as they are supposed to be). :)
     
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  6. oldhank60

    oldhank60 United States Active Member Active Member

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    I spent my hard earned money on buy expensive tools to set up both my mills and lathes, I have found in the long run it saves me time not having to put indicators and change base's around to fit what I am setting up either the mill or the lathe,
    I do not work for the company I got all most every thing I use from but I will say they are top of the line from tramming your mill table and setting vise on table correctly
    what I like the best are the lathe tools, setting correct tool height will always make a better part no nub in center you can set slitting blade correctly, dial in a 4 jaw chuck with no fuss and they also make a precision bar to set the tail stock that don't cost a whole lot of cash,
    the company I am referring to is edge technology, the make tools for manual engine lathes and CNC lathes and Mills

    hank kettler


    most probably already know of these tools but to those who don't check them out, again I am not sales person for them or anyone else
     
  7. dlane

    dlane Active User H-M Supporter-Premium

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    I tried the Edge mill tramming tool with the two dial indicators , sent it back to them
    The cheep chi indicators were not repeatable ,so I made my own with good indicators
     

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