Evaluating a Taft-Peirce Surface Grinder Damaged in Shipment
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  1. #1
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    Default Evaluating a Taft-Peirce Surface Grinder Damaged in Shipment

    I purchased a very nice Taft-Peirce Number 1 several weeks ago, sadly it was damaged in shipment. The seller has now refunded my money and as a bonus I get to keep the machine. Its almost criminal the machine was damaged, as it appears to have been in excellent shape. Upon delivery, it appears the machine maybe in better shape than originally thought it was during inspection at the trucking yard.

    Whats damaged:

    1. Table ball retainers are missing and damaged (chunk left)

    The v-ways appear to be in good shape, no signs of brinnelling. Just trace marks from the balls, don't feel n edge with my finger

    2. The ball retainers are damaged, one missing completely. Along with table stop.

    This appears to be made from phenolic, but I am tempted to remake them from delrin or teflon. The table stop is a simple rod with tapped ends.

    3. Spindle Assembly, one of the edges of the motor casting was polished and worn, maybe from rubbing the wall of the truck-trailer?

    I cleaned the spindle, and put my tenths indicator, no movement to the slightest movement, maybe 25 millionths??? I then put some weight on the spindle and it moved 3 tenths, but snapped back to near zero with force removed.

    I then powered the spindle motor, it spun like a top. Very quiet and smooth.

    4. Machine in general:

    Scuffs, the soft line from the Bijur oil can is broken. And the x-axis handle wheel slightly rubs in one spot, could be adjustment.

    5. Fine adjust verniers.

    I was able to check the z-axis, one adjustment of the tenths scale, drives the z-axis one tenth. There is back-lash when changing direction, but its right on when driven.

    6. Y-axis tilt.

    With the table removed I placed the best and heaviest parallel (.0001-0002 flatness)I own on the x-axis v-ways. I placed two balls under the parallel on each v-way, and held the parallel in places with magnetic indicator stands.

    I set the indicator to zero, and worked the y-axis out towards the operator. I got a total of about .0009" across 5.5 to 6". I was able to get the number down to around .0005 or .0006" by placing about 20 pounds on the table, I think without the weight off the x-axis table and chuck, the y-axis cantilevers a bit. I may also be able to attribute some of that tilt to the protective tins, as I can hear some of the tins rubbing the saddle in the first few inches of trouble. Its also evident the machine should have the saddle removed for cleaning.

    Has anyone pulled the saddle on a TP? Any tips?

    It seems the machine can be saved, any thoughts?

    Thanks,

    Marco



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  2. #2
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    I've rebuilt three of those, all became nice machines; and all in far worse shape than yours when I got them. End retainers, table stops all pretty trivial, precision bearing balls are too cheap to not replace..

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    As far as your "Y-axis" (actually Z-axis; Y-axis is spindle up/down) misalignment, couple things: yeah the weight will certainly affect it. You want it a little high on the "away from the spindle" side. Your measuring method is mostly fine, BUT, your indicator setup is not. While it is possible to use a test indicator for actual measurement, you must insure that the lever/probe is at the proper angle to the work axis you are trying to measure (due to cosine errors) if you want to get accurate dimensions. In your photo it looks like yours is almost at a 45° angle, which will introduce a quite significant amount of error in dial movement. Most indicators are spec'd for the lever/probe to either be as nearly flat to the work as possible or some I've seen are spec'd at 15° to the work. So your 0.0009" figure is probably not accurate.

    Regarding axis designations, spindle in/out inline with it's rotational axis is generally always Z-axis on a machine tool. Moving the spindle in space or the machine table perpendicular to and relative to the spindle is X and Y.

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    Sounds like your machine is in much better condition than most.
    Not sure what you are designating X and Z, but the fine adjusters on either axis have lots of backlash inherent in their design.
    The in/out of the table ( we call that Y here, other shops designate it differently) has an adjustment feature that eliminates backlash on the main feed screw (not the tenths fine adjust).

    Don't think the table ball bearing retainer material is critical, delrin or teflon should be fine.

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    Thank you for "learnage" guys. I will repeat the measurements of the in/out of the saddle (z-axis) with the indicator at the proper angle.

    Colt45, any tips on stripping the saddle? I would imagine the handle hubs need to be removed (tight fit onto the shaft), then the micro adjust mechanisms.

    Also, it looks like there is a mechanism eliminate/adjust saddle play (left to right), any tips? I would imagine it needs to come off first.

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    Quote Originally Posted by eKretz View Post
    Regarding axis designations, spindle in/out inline with it's rotational axis is generally always Z-axis on a machine tool.
    This is generally true, except when it's not.
    One notable exception is the convention for Deckel style milling machines- Z is always the table moving up/down. When the vertical spindle is used the spindle designation is Z, but when the horizontal spindle is used, it's designation is Y; there is also an X designation for the vertical spindle tipped horizontal. I've seen very experienced grinding professionals refer to the table in/out on surface grinders as Y.

    Been quite a while since I pulled the Taft Peirce saddle (probably about due for a cleaning right now), best recollection is it's slightly complicated but not too bad and easier with 2 people. Suggest you sweep and mop around the machine, vacuum and wipe your machine down and let things settle before you start so that you don't contaminate inside the exposed machine ways. Set up clean table tops with fresh paper towels or clean rags so you have a place to put things as you take them apart.

    I would remove the table first, then all the handles/knobs, followed by the front faceplate behind the handwheels, then the in/out backlash adjuster. Takes some time because you have to load/unload the cross slide bearings, I think on mine they are individual ball bearings, maybe rollers.

    Suggest care installing and removing the dust covers, they are easily damaged and very difficult to source replacements.

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    There are lots of experienced fellows who never bothered to think or learn about axis designations and just go with whatever it's originally introduced to them as. A machine like a Deckel mill is a very unusual case since it has two separate spindles that are in different orientations. The same goes for machines that have a tilting head. The reason for this is probably twofold. First, the labels on a DRO aren't usually able to be easily changed, and secondly it might get confusing pretty quick if a guy is operating a machine and gets used to it, then all of a sudden the axes change designation.

    The correct designation for table or head in/out movement towards or away from the flat side of the wheel on a surface grinder is Z. You can probably look that up on surface grinder manufacturers' websites with Google pretty easily if you need confirmation.

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    Removed the handles last night, all went real smooth except for the z-axis, it was ridiculously tight, tight enough for me to but the perfect fit spanner wrench. With the nut removed, the handle came out smoothly.

    Regardless of shipping damage, I am glad I am pulling the saddle. It is filled with metal powder.. See the photos.

    The saddle is next, I think the best way to pull it is to removed the saddles center balls/tracks. Simply by removing the bumpers and pulling them one at a time. The saddle should lift off, with some luck I should not have to have to reset the adjustment, but I will see if i can get some measurements to side to side play.

    So far this machine uses balls on the X-axis, cylinders on the Z-axis outer, balls on the Z-axis center track, and I am not sure about Z yet (hopefully I wont need to pull them).

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    From what you have written so far, and what others with experience have said, you'll be able to get the machine working properly without too much pain. Note that you might also get some interesting and useful feedback in the Machine Reconditioning, Scraping, and Inspection forum. I suggest you start a thread there as well, with a photo or two of the long ways and the entire machine.

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    Table is ready to come off, just need a second hand lift her up. The table is freed by removing the centers ball tracks, once removed the table can be lifted.

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    Got the saddle removed and pondering about replacing the rollers, I cannot find anything off the shelf. The rollers look okay, but they very in diameter a .0001, .2557-.2558". I have asked deltronic to quote me on qty 50, we will see what the price comes back at.

    I found a really good grinding house, I am considering just having my rollers kissed a few tenths so they are all the same. I don't think anything in the machine a alignment would be affected by lowering the saddle a few tenths, as the all of the handle assembly's have a few thousandths of float in the bolts that hold them in place.

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    Photos showing grit. I think the right thing to do at this point is to remove the column for cleaning. I think it would need to come straight out with a hoist. Has anyone pulled the column?

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