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  1. DennisP

    Grinding vs turning

    2.0 Ra is far from a mirror finish. The only means to remove 400 microns in a single pass would be to turn it. I typical ground finish would be closer to 0.4 Ra, but with 400 microns of stock to remove, would take multiple passes. Surface finishes of 2.0 Ra are easily attainable with turning. A...
  2. DennisP

    Measure round corner

    Depending on the configuration of the part, an optical comparator might work. You could also use a CMM or a linear form tester such as the Zeiss Surfcom.
  3. DennisP

    Growth of Material in Heat Treat

    Thanks for all the valuable information. We are using 52100 and thru hardening to RKW 30N 77 Min.It's been our experience that each heat acts a little differently regarding the growth in length after heat treat, even in a well controlled heat treat process. Enough so that we need to perform a...
  4. DennisP

    Growth of Material in Heat Treat

    Does the reduction ratio of the raw material have any bearing on the rate of growth of a part in heat treat? For example, given a single heat of steel, one bar drawn to a diameter of 1" and one bar drawn to a diameter of 1/2". The 1" bar is turned to produce a part of .45" diameter as is the...
  5. DennisP

    "Killing" of a nut on an anchor bolt

    If there are no threads exposed as the OP stated, a jam nut will not work.
  6. DennisP

    Caliper Selection

    You'll be hard pressed to find ANY calipers capable of measuring +/- .0005" accurately. They may have that sort of resolution, but will never pass a GRR at that level. In the precision machining world I live in, calipers are not used on tolerances less than +/- .005". I'd suggest an indicator...
  7. DennisP

    determine flywheel weight

    More important for Ford small blocks is to get a flywheel with the correct balnce weight. Ford used 2 different balance weights on the balncer and flywheel over the years, 28 ounce and 50 ounce. If you don't have the correct one for both the balancer and flywheel, the engine will shake itself...
  8. DennisP

    What does this mean?

    It specifies that a raised edge of up to .1 is allowable.
  9. DennisP

    MacPherson Strut Spring Installation

    I would think it's due to the fact that the spring in it's full extension position is somewhat nonlinear regarding rate. But if you start with some preload the rate is more nearly linear.
  10. DennisP

    Is this sampling method tighter than before?

    Coming from a machining and quality background, wouldn't it be better to find a way to stabilize the process rather than rely on inspection to insure good parts? Have yopu performed a capability study to determine whether or not the machine is capable of running the part with good control and...
  11. DennisP

    Verify NPTF thread with L1 and L2 Gage

    Absolutely. The L1 checks the pitch diameter of the threads, which will change by 4x the plating thickness after plating. The L2 is probably not as critical, but the minor diameter will also change some due to plating buildup on the crest of the threads. The unplated thread form must be modified...
  12. DennisP

    surface finish question

    No. The cutoff length is the length over which the trace is evaluated. Generally the length of trace is made up of 6 cutoff lengths. Example: length of trace 1.5mm would have a cutoff length of .25mm. The cutoff length is generally selected based on the periodicity of the surface finish.
  13. DennisP

    Cad Pre-Plate Thread Dimensions

    Craig, Glad I can be of assistance. It's unfortunate that there is so much variation in the plating thickness, especially for class 3 threads. Could a plating that is more controllable in thickness be substituted for the Cad?
  14. DennisP

    Cad Pre-Plate Thread Dimensions

    We run parts at pre-plate dimensions all the time. For external threads, the pitch diameter low limit is decreased by 4X the low plating limit, and the pitch diameter hi limit is decreased by 4 x the hi plating limit. This decreases the as-machined pitch diameter limits and requires a tri-roller...
  15. DennisP

    How to use NoGo thread plug gage?

    In that case, I would consider the threads to be OK.
  16. DennisP

    How to use NoGo thread plug gage?

    Our standard for No Go thread gages is that the gage can go no more than 3 turns. The information comes from Machinery's Handbook. Unfortunately, with only 3 threads, this creates something of a dilemma. Do you feel any drag after 3 turns? If it is a ring gage, are you sure the lead threads are...
  17. DennisP

    Surface Rougness Cutoff Length

    The general rule is for the cutoff length to be 1/6 of the length of trace. This is the value we use unless our customer specifies otherwise. It is also the default value used in most surface finish test devices.
  18. DennisP

    316 SS RoHS Compliance

    Unless I miss my guess, the other is probably iron as it is still a large part of the chemistry of stainless steel.
  19. DennisP

    Perpendicularity callout

    Thank you all for the responses. We're going to get back with the customer and have them spec it properly.
  20. DennisP

    Perpendicularity callout

    I have a print that has a perpendicularity callout on an end face of a cylindrical part of .25% to DATUM X, which is the OD of the part. I'm familiar with perpendicularity, but have never seen it called out as a percentage. My question is , a percentage of what?

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