50 Tidbits

Post date: Aug 22, 2014 3:43:14 PM

50 Tidbits by Dave Arneson

1. Cross check your measurements with a lesser accuracy gage

2. Always push on your indicator stand to see if the needle comes back to the same spot

3. Don’t assume your grinder ways are worn out when you can’t hold size anymore, it might be your tailstock that’s worn out.

4. Invest in taper stones to remove burrs and scratches from center adapters and tool holders

5. Don’t necessarily believe the gage with the highest resolution

6. Always wring up 2 stacks of gage blocks

7. How you hold on to a part is probably going to be your greatest source of error

8. A 3 jaw chuck doesn’t necessarily bend your part 3 lobe

9. 60 degree centers are a gift from God

10. Check to see if your indicator tip is loose

11. Look for flats on your indicator tip

12. Counter drill your tapped holes

13. Bigger screws don’t necessarily make for a better bolted joint

14. Ground surfaces go together better than lapped surfaces

15. Put light bulbs inside your machine base to keep the base from getting too cold in the winter

16. Remember that you are a big source of heat

17. Make sure you soak your part long enough before you measure it

18. Always stone your parts

19. Always stone your surface plate

20. If you want to do a very fine infeed try bending your machine

21. A soft hammer works well to move a plain way machine slide a very small amount

22. It is perfectly reasonable to level your machine

23. Balance your grinding wheel

24. Most machines can be made to be much more accurate by replacing the work spindle with a Blockhead air bearing

25. Don’t necessarily assume that your spindle is bad because your parts are

26. Everything is rubber when you measure in microinches

27. Get yourself a good used Mikrokator

28. Most machine tool slides are very well made; the biggest deficiencies in most machine tools are their work spindles and their tool/work holding

29. There is nothing magical about 20 degrees centigrade; what you really want to do is avoid temperature gradients and fast temperature changes

30. Don’t pour warm coolant over a cold machine and expect not to have trouble

31. Don’t pour cold coolant over a warm machine and expect not to have trouble

32. Check your gage calibration over the range that matters to you

33. Electronic gages need good batteries even when you have them plugged in

34. Invar’s coefficient of expansion is as far away from steel’s as aluminum's

35. Worry about your material’s thermal conductivity as much as you worry about its coefficient of expansion

36. Know what you are measuring; often what you think you are measuring is different from what you are actually measuring

37. Generally the more massive your indicator mount is, the better your measurements will be

38. Make sure your screws are properly tightened

39. Things bend when you tighten screws

40. Collets only work correctly when your part is the right size

41. Your spindle’s drive is very often the main source of spindle error motion

42. Air regulators are not created equal; get a good regulator and consider cascading if you want to do precision work on an air bearing spindle

43. Don’t necessarily believe your diamond grinding wheel salesman; he might want to sell you a wheel that lasts a long time and your parts might be better with a less durable wheel.

44. Running your grinding wheel at a slower speed sometimes gives you better parts

45. Don’t run your wheel at your machine’s natural frequency

46. Lessons learned from diamond turning don’t always transfer to other kinds of precision machining

47. Donaldson Reversal isn’t a very practical a way of separating spindle error from ball error

48. In spindle testing it is very important to have your master sphere integral to its mount

49. Running your CMM slower can increase its accuracy; the formula that tells you how accurately you can measure with your CMM assumes fairly fast measurements

50. Granite Dents