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andy_b
11-15-2007, 10:58 AM
have any of you "home shop" guys used a die head for threading? if so, how did you use it (in a mill or lathe or somewhere else)? how much are the various inserts? i saw one recently and was thinking it might make threading easier for common thread sizes. i'm sure it would be expensive to buy the inserts every time you needed to make a one-off threading job.

andy b.

Carld
11-15-2007, 11:12 AM
I have used them in one shop I worked in. They are mostly used in production work. It don't take long to set them up but you do have to have the die sets for each thread you will cut. I would only use one if I were theading several pieces as it definatelly is faster then.

They are to expensive for most shops but you can get them on ebay.

I got lucky and scored three heads and four trays of dies from a friend. I may never use them but like my uncles kwikway boring bar I will keep them around just in case.

DR
11-15-2007, 11:46 AM
have any of you "home shop" guys used a die head for threading? if so, how did you use it (in a mill or lathe or somewhere else)? how much are the various inserts? i saw one recently and was thinking it might make threading easier for common thread sizes. i'm sure it would be expensive to buy the inserts every time you needed to make a one-off threading job.

andy b.


Not exactly a home shop type....but I've used die heads extensively. We use them in CNC machines for threading rods all the time, especially in sizes like 10-32, etc.

Generally, they're used in machines where the die head is non-rotating and the work is rotating, this usually implies a lathe. There are heads meant to rotate, but those are specialized.

Good quality die heads retail in the over $1000 range with chasers (inserts) $100 plus per set. They can be found at auctions and on ebay for a fraction of new price.

Geometric brand heads are popular. Myself, I prefer the tangential style heads like J&L and Landis.

Setting up for a one-off part would be time consuming.

Malc-Y
11-15-2007, 03:37 PM
I bought a 3/4" Coventry Diehead on ebay last week for 15 [$30] and some chasers for abot 2 or 3 [$4 or $6] each. I havn't used them yet but they are ideal if you have a capstan unit on your lathe. The price for new dieheads and chasers doesn't bare thinking about!

Malc. :cool:

andy_b
11-16-2007, 12:07 AM
thanks for the replies! if i come across a deal on one (meaning CHEAP) i may pick it up. it does sound though that for an occasional use for more than one or two types of threads it would probably be expensive and impractical.

andy b.

Ian B
11-16-2007, 01:24 AM
Good post Andy,

I've been considering exactly the same thing. I'm guessing that you don't have a capstan type lathe, just a centre lathe like the rest of us mortals.

It seems that the options are then to hold it in the tailstock, leave the tailstock clamp loose and let the work drag the tailstock along the bed, or to make up a holder for the toolpost and drag / hand feed the carriage. I'd probably go for the latter.

What's putting me off at the moment is the setting of the thing - you're relying on the dies snapping out at just the right moment. If they don't, I suppose the thread strips or something gets damaged. Looks like a lot of setting up to cut a few threads.

The bits are certainly cheap enough on Ebay, and I think that a set of dies will cover a range of diameters for a given pitch. John Stevenson (aka marypoppinsbag) sells a CD on Ebay, covering the die heads - this would probably be an excellent place to start.

Another alternative is to forget about the die head and just buy the dies; make up a toolholder, use them one at a time as screwcutting tools and cut the threads with the leadscrew as you would when single point threading - same nice threadform, probably just as quick.

Let us know if you do buy one, and how it goes...

Ian

DR
11-16-2007, 04:53 AM
The bits are certainly cheap enough on Ebay, and I think that a set of dies will cover a range of diameters for a given pitch.

Nope, not on any I've used.........each/pitch diameter combination needs it's own set.

Timleech
11-16-2007, 05:58 AM
Nope, not on any I've used.........each/pitch diameter combination needs it's own set.

Essentially true, though there is a small range of adjustment (on Coventry dieheads, and I expect on others).
I did find a diehead very useful when I needed to make some long 10mm x 26 tpi threads, that's well within the range of 3/8" x 26 chasers.

I've used them quite a bit mounted in the toolpost or in a specially made holder behind the toolpost, I've not tried them in the tailstock. I know people do it, but I honestly thing you would struggle to keep up unless you have a lever taisltock.

Tim

Carld
11-16-2007, 10:06 AM
They really work better in a turret lathe because you can set the travel stop to get length of thread and release at the right spot.

When I use the Geo head in a manual lathe I run at about 75 rpm and put a mark on the part where I want to stop. When the threads are cut near the line I reverse the hand wheel rapidly and it kicks out the dies. You have to be awake and on top of it to do it that way.

I have been thinking about making a lever feed for my current lathe like I did for the Logan I sold my son. They are handy for drilling and threading and using a tailstock turret that goes in the tailstock quill.

andy_b
11-16-2007, 02:09 PM
Another alternative is to forget about the die head and just buy the dies; make up a toolholder, use them one at a time as screwcutting tools and cut the threads with the leadscrew as you would when single point threading - same nice threadform, probably just as quick.


Ian

there was a post on here a few years back that i think involved a holder for just what you are talking about. at the time i was too new to have much idea what was being discussed, and wasn't ready to try making threads yet anyway. maybe whoever wrote that original thread will recall it and chime in.

andy b.

thistle
11-16-2007, 02:21 PM
i am mildly interested in getting one , but have not read up enough on them to start buying off ebay sight unseen -

here is the results of a google search of the PM forum about die headss

http://www.practicalmachinist.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=1;t=020862;p=0

motomoron
11-16-2007, 05:33 PM
I have an Acme and a Geometric. I was "permanently" loaned the Geo by an associate to use on a frequent job cutting 5/16-24 threads on 4140 rod. I only have a few chasers, but only bother to set up if I have 10 or more pieces to do. Once the job is set up, though, you can crank out cleanly threaded parts really fast.

moldmonkey
11-16-2007, 08:44 PM
I bought two die heads, a 5/16" geometric and a H&G that takes Series 100 chasers. Actually, they came on a Hardinge DSM-59, all for $100.:D I don't have any useful sizes of chasers yet so I haven't tried them yet.


I have seen references on one of the forums that it is best to have two, one to rough and one to finish. Is this true? Hopefully, not as I won't be able to afford to tool them up for a long time.

Any other tips on using dieheads would be appreciated as they are new to me.


TIA, Jon

beckley23
11-17-2007, 12:23 AM
The only thread I chased in 2 cuts, rough and finish, was a 1"-8 in 303 SS, using a 1" Geometric D style head, only because the shank has been modified, and I was worried about slippage. I forgot to reset the head for the rough cut on one part, but fortunately no problems. All the rest I do in 1 cut, so far. The problem, at least for me, is picking up the thread on the 2nd cut, but I seem to get a lot practice when I do some 12" long threads on one job from lack of concentration on advancing the turret with the thread pitch, and premature opening. Gotta stop and go back to the beginning, and start over again. The slower the spindle is turning the harder this gets, trust me on this.
I believe that Machinery's Handbook has a section on speeds for threading with die heads. Geometric's handbook recommended 38 RPM for the above mentioned thread and material, my turret lathe has 2 speeds close to that, 30 and 44, I opted for 44, and I did have a couple of premature openings, and the thread length was only 1-5/8".
Several years ago I had a job of increasing the thread length from 1-1/2" to 3" on 2000pcs 304 SS bolts. The recommended speed was about 100 RPM, but I gambled on doubling the speed to 220 RPM, and won. I did have to sharpen the chasers a few more times, and I did have several sets ready. That gamble paid off, but I haven't tried it since, and I don't recommend that you try it, unless you're willing to pay the price.

There is a lot of information in the Geometric handbook that I haven't seen anywhere else. The hook angle, lead -on champfer, speeds, and material all play important roles in successful die head threading, and I never let a tool and cutter grinding shop sharpen my chasers. Been there and done that, bad mistake.
Harry

Rich Carlstedt
11-17-2007, 01:13 AM
I have two, a 9/16 and a 3/4 Geometric.
They are fun to use in a home shop..
I have found that they do allow a range of diameters of about 2 numbers.
That is, I can take a 8-32 and cut a 6-32 or a 10-32 with the same dies.
This has allowed me to cut threads i do not have the dies for !
It is harder to go smaller than larger.
Since I have the "D" model ( auto stop ) I do the following if i am making say 20 screws.
I will cut a plastic ring (1/8" stock or heavier) that snaps on the outside of my 3 jaw chuck JAWS, when the work is clamped. Then as I am threading, the push stop lever will hit the ring and spring the die open.
I also use a very tall thin aluminum angle clamped to the inside of the rear way to trigger the stop lever.
Rich