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  1. RRBD

    "Normal" CNC mill and CNC lathe tolerances in aluminum

    Sorry for offending you... If I had a Quarter for each time I answered the question of CNC capabilities an then recieved a print that was way over-toleranced, I would have quite a collection of Pop money. The sad fact is, that most Engineering courses don't spend adequate time teaching proper...
  2. RRBD

    "Normal" CNC mill and CNC lathe tolerances in aluminum

    Cosmetic features don't need to be held within .005 in my opinion. You still have a guy trying to measure it with a caliper when all he really needs is a scale or tape. Dimensioning according to form,fit, and function applies to everything, even cosmetic features. If you want something cut to a...
  3. RRBD

    Maintenance vs. Operations

    The pissing contest between, maintence and manufacturing dept's is really common and will cause you many headaches.I have went through the "ropes" in the previous posts to remedy the same issue and what I finally came to is very easy. This solution worked well for a major machine tool...
  4. RRBD

    "Normal" CNC mill and CNC lathe tolerances in aluminum

    This is a poor way to go about a design IMO. Tolerance the part according to necessity of form, fit and function. Why tolerance it +/-.005 when +/-.125 will work fine,regardless of what a machine is capable of. If a part can be sawed to length, and the machining done with a roughing endmill then...
  5. RRBD

    Why out-of-round holes?

    Boring is way more accurate than reaming. You state that the holes are bored, are you sure? Are all parts consistant, as in out of round the same way? This problem will be a simple fix, like clamping pressure,or "bores" are being interpolated in a mill with bad axis compensation. If its a...
  6. RRBD

    I need a Good Reamer

    The accuracy of a reamed hole lies mostly in the operations leading to it, if you are just stabbing a drill in these parts and then reaming the hole, I can see the trouble. I usually, drill, plunge with an endmill and then ream if possible.An endmill will make the hole round, on location. A...
  7. RRBD

    Port comparison

    Remember, a port the flows well at low lifts will also flow backward well too (reversion)You need to try a few things to determine what is happening, I would try moving the head a small amount so the valve is closer to the centerline of the cyl. bore and retest, this will tell you if the valves...
  8. RRBD

    CNC positional tolerances

    First, I try to avoid putting the heads of fasteners in a place they cannot be reached for service in the field(ie: the mounting side of an enclosure)Second,when c'sinking holes in thin sheet metal, there is no sense drilling a hole and then opening it up again with a chamfer, find/grind a...
  9. RRBD

    How best to ask for CMM data ?

    Your sub is probably accustomed to reading the same data he gives to you. Heres what you do...Make your own conformance report, have a drawing and a couple of columns, one with the print dimension and the other they fill in the actual dimension and require they fill it out and sign it off, it...
  10. RRBD

    CNC positional tolerances

    Here's the deal, most CNC are very accurate and repeatable to within tenths. The tolerances come when you start putting tools in the spindle. Take drilling for example, I find that I can generally hold a tolerance within .003" of nominal when drilling using a screw machine length drill. You can...
  11. RRBD

    Converting to roller crank bearings?

    Agreed, dont waste your money. A properly designed insert bearing set up should last a very long time. A common problem in high rpm applications is the main caps will "pinch" the crank, which in turn will wipe the oil wedge away, which means crank to bearing contact and shortly after the engine...
  12. RRBD

    Machinist sayings or "quotes"

    Dead nuts is when you have to check and make sure the indicator is actually touching the work piece....... Funnelguy, you need to relax. When a machinist tells you its a hair off, you should count on atleast .003" out of tolerance, if it was only .0002" most wouldnt even come to see you. I...
  13. RRBD

    thread start position

    The lead/pitch of a metric thread is noted in its description, M66 x 1, "66" being the diameter and "1" being the lead or pitch,of, 1mm per rev. No handbook required.
  14. RRBD

    Gaulding or "galling" of morse tapers

    I would advise against lapping the two tapers together, especially if you want to get them apart again. Most tapers are ground with with slightly different angles (seconds) which is why they come apart when needed. A tang drive sounds good. I know it sounds funny, but, chalk will help this...
  15. RRBD

    thread start position

    I would not recommend it, but if you must,here's my two cents. 66 x 1 is very big diameter with a really fine pitch. Considering you will be cutting an internal thread,I would mill the threads,which will make it easy to orientate the starts of each. Next,I would try to use the minimum an maximum...
  16. RRBD

    Throttle Body - What size do I need?

    What devices are you using to provide feedback to the Haltech? MAP sensor,TPS,and o2 sensor? What are you running for headers and where is the o2 sensor located and what style is it(1 wire,3 wire)? What is your BSFC or AFR at peak? If you are using a MAP sensor,it may be telling the Haltech...
  17. RRBD

    Throttle Body - What size do I need?

    If it is a 4 bbl throttle body,with 1-5/8" bores it is more than enough. Think of the popular 3310 Holley of the old days. I would start looking else where. What heads & intake,what valve springs, what cam(LCA&DUR@.050)? If you're using an old HEI, it may not be up to task. Need more info about...

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