Acme threads

[Jammer™]

How do you machine internal acme threads? I have no expierience in this. Thanks

[Lumpnut]

Would one of these work for ya ?

 

it's at the bottom of the page

[Philcott]

Jammer,

 

The larger sizes can be machined like any internal thread using thread bars and inserts but the small ones can be tough to do. There was a thread on this a year or so ago so try searching for it. The main problem is trying to find a bar that will hold an acme insert that doesn't require a large minimum hole diameter. We have had custom carbide (and HSS) bars ground up to make smaller dia threads but due to the nature of the contact area being large and therefore deflecting the tool on acme threads, we have found staged taps to give us the best results.

 

Good luck,

 

Phil

 

Edit: NuNu. those bars are like the ones we had made up. Worked well in alum and brass.

[Jammer™]

NuNu, Yes that would work. Thanks. I was just trying to stay away from thread milling because I only have about 1/2" of thread depth and it's in brass. I seen in Machinery's handbook that there is actually acme hand tap sets. Familier with these?

 

Thanks for the replies guys.

[Philcott]

Jammer,

 

Some of the taps are made so the first stage roughs the thread and the second stage finishes them. This kind of tap works real well, in brass, but of course needs to have a through hole.

 

Phil

[Lumpnut]

+1 Phil

 

Jammer , check page 230 of the MSC book.

 

[CAM-mando]

Assuming you are talking about lathe work ????

 

For the smaller sizes we use the rough / finish style taps for manual toolroom work and threading bars on the CNC's.

[Jammer™]

Thanks guys.

[kinglouie V]

in my experience with some metals it's best to start out with a tapered reamer then use the tap. However, with brass you shouldn't have trouble although it may look better to ream first.

[Racer X]

I just went through an ordeal like this. I had to tap steel, however. I had a two stage tap custom made for a proprietary 18mm acme thread. I will get you the name of the company that made it for me in the morning if you like. It worked great and was priced less than MSC.

 

Cheers

[crazy^millman]

I use ot threadmill them, tap them and trun them and Threadmilling gives you the ability to make a full thread to a should cloder than turning. Turning gives you a better finish IMHO. I use to do a 2" #4 Acem in 12L14. I took a Cobalt toolblank and made the correct acme profile then I silver solidered it to a piece of what we caled ETD-150 or 4150 ht. It did about 65 parts beore I hade to cut it off regrind it and braze it back on.

 

HTH

[Racer X]

Here is the web addy for the folks I used.

 

Hope this helps.

 

http://www.widell.com/

 

Cheers