Cutting multiple-start screws on old screw machines
 

Hi,

We're interested in producing (in relatively large numbers) 1/4-28 UNF 1/2"
Long screws with a quadruple-start. We're thinking of buying an older
(cam-type) screw machine to dedicate to this part. The question is, can
these cam-type machines (e.g. Acme-Gridley, Brown & Sharpe, etc.) cut screws
with multiple starts?

Thanks in advance,
James

Cutting multiple-start screws on old screw machines
 

James H. wrote:

Hi,

We're interested in producing (in relatively large numbers) 1/4-28 UNF 1/2"
Long screws with a quadruple-start. We're thinking of buying an older
(cam-type) screw machine to dedicate to this part. The question is, can
these cam-type machines (e.g. Acme-Gridley, Brown & Sharpe, etc.) cut screws
with multiple starts?

Thanks in advance,
James


I can't help you, but I do have a naive question: Does 1/4-28 4-start
mean that there are 28 threads in each inch (with the thread lead being
1/7 of an inch) or does it mean that the lead is 1/28 inch and there are
106 of them?

Either answer is impressive, in its own way...

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Cutting multiple-start screws on old screw machines
 

I can't help you, but I do have a naive question: Does 1/4-28 4-start
mean that there are 28 threads in each inch (with the thread lead being
1/7 of an inch) or does it mean that the lead is 1/28 inch and there are
106 of them?

Either answer is impressive, in its own way...


Tim, it means that the pitch remains at 1/28 but the lead is 1/7 (4:1
ratio), which means that turning a nut on this screw advances the nut
four-times the distance that would be travelled by a regular nut on a
regular 1/4-28 screw, but both nuts would have the same number of threads
engaged.

Cutting multiple-start screws on old screw machines
 

According to James H. :
Hi,

We're interested in producing (in relatively large numbers) 1/4-28 UNF 1/2"
Long screws with a quadruple-start. We're thinking of buying an older
(cam-type) screw machine to dedicate to this part. The question is, can
these cam-type machines (e.g. Acme-Gridley, Brown & Sharpe, etc.) cut screws
with multiple starts?

I believe that these machines don't have a thread-cutting
leadscrew and gearbox, so threads are most often cut with something like
a Geometric die head.

You'll have to get in touch with Geometric (or any of the other
people who make chasers for such die heads) to find out whether they can
make a special set of chasers to do this.

I suspect that they can -- and may provide the chasers for about
double the cost of standard chasers.

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Cutting multiple-start screws on old screw machines
 

Where I used to work we rolled threads with an automatic thread roller. As I
recall, we had it mounted at the twelve o'clock position on an eight spindle
Conomatic. We had a few Acme's set up for thread rolling as well.

Multi-start thread rolling dies might be available already, or could be
ordered I suppose.

Hope this helps,

Tinker

Cutting multiple-start screws on old screw machines
 

Large numbers of threaded screws are most often done by thread rolling. The
threads are better then cut threads.
I remember running a 1000 piece order of threaded 17/4
stainless rod ends that called for a 5/16 left hand fine thread . And by
mistake we had then threaded right hand.
So we talked to the thread roller and he rerolled them straight then
rerolled them to the correct left hand thread.
These parts were aircraft parts. Which makes me think you might be able to
use stock 1/4 bolts to do the same
thing if the thread rollers can make a die for your parts.
If I remember correctly the thread rolling company was
called Ace Grinding in the Los Angeles area. Hope this
might be of help to you.
Jim

"James H." wrote in message
news:S%Cvf.33264$tl.21318@pd7tw3no...
Hi,

We're interested in producing (in relatively large numbers) 1/4-28 UNF
1/2" Long screws with a quadruple-start. We're thinking of buying an older
(cam-type) screw machine to dedicate to this part. The question is, can
these cam-type machines (e.g. Acme-Gridley, Brown & Sharpe, etc.) cut
screws with multiple starts?

Thanks in advance,
James