What is the difference between the theoretical percentage of a thread compared to the percentage of a full thread. When I use the formula tpi*(tap od - drill od/.01299) I come up with a higher percentage than what is on the drill and tap charts.
Why can I not find a H40-DDQNR4 boring bar in any of the tooling catalogs? They have external tool holders in the 17.5 deg orientation "DDQNR" but only 3 deg "DDUNR" for boring bars. Any help would be greatly appreciated.
This is an awesome web site. First time I ever posted a question and look at all the response. It is very nice for a change to get other people's idea's who deal with these problems daily and know what it is like. It gets very old trying to explian why there is a problem with a part and have...
Funnelguy,
Kinda close. First of all this is just one example of a part with a long bore to diameter ratio. That is the problem that started this thread. You are right that this part has a thru bore. The work piece will start as a solid bar sawed long. Then put in a turning center and...
funnelguy,
The part is a 20deg spur gear. Pretty basic part, just turn the blank, cut the teeth, keyway and setscrew. Need to hold .003" t.i.r. for teeth cutting. Thought maybe about a bore releif with no surface finish and more tolerance. Then just match bore the two ends.
The part that started this thread has a 12.250" L.T.B. with a 1.689" bore dia ±.0005" and hold a 63 finish. The material is 4340 pre heat treat 28-32.
I am very interested in all the responses about gungrilling. What kind of tolerance and surface finish can this process hold. Are there many vendors out there that provide this service and if so at what cost and turn around time?
I am looking for any guidlines or references on bore diameter to length ratios. Our sales dept is having difficulty quoting jobs properly. They take orders for parts that have extreme bore diameter to length ratios. In the manufacturing dept we try to stick with a 3x ratio for steel boring bars...
