Author Topic: a question about dies (Read 9163 times)

stirling lad · « **on:** June 04, 2014, 07:56:23 PM »

Hi Gents,,

sorry but i've got another question for you oh wise ones.

.....I could'nt afford to buy split dies for a part I'm doing so I bought a cheapo set of unf/unc taps & dies but when they arrived this morning this is what I saw..

Now I've read of dies sold elsewhere that can be cut to make split dies or just left as is if you only need rethreading dies..
so the question is...Are these that type of die? and if not why do they have the slot and dimples when their die holder does'nt have screws to fit the left/right dimples?

...Mike...

vtsteam · « **Reply #1 on:** June 04, 2014, 08:02:39 PM »

Wouldn't a die be pretty hard to try to cut even with a starting groove?

Well I guess it would be possible with an abrasive disk, but it's hard to see how it wouldn't hurt the thread. At least in my hands!

Anyway, I don't know the answer here to why this die has the grooves and dimple except as a guess to make it universal to fit a variety of handles. Of course it could be meant to split after slitting and the dimples used to adjust the gap....

stirling lad · « **Reply #2 on:** June 04, 2014, 09:04:17 PM »

I think the thread should be ok as the groove would come out in the hollowed section,,In the other forum some guys from somewhere in Europe had'nt any idea what split dies were and they said that they were'nt available where they were,, ( I think it was Sweden or Denmark but I'm not 100% sure) they were discussing it with some Brits,, and their conclusion was that if these were all that was available then they must be optional,,,I thought at the time that that was a large jump to a conclusion but did'nt have any knowledge to contribute to their discussion... the dies seem to be a half decent quality though as they have a quite obvious taper to the threads..as you can see on this photo..I don't know if that's of any significance but they do seem better quality than i was expecting..
...Mike..

stirling lad · « **Reply #3 on:** June 04, 2014, 09:07:39 PM »

Ive heard of little red discs from dremel sets being used to cut dies and their supposed to be very brittle though..I have some of the black cutting discs and a similar dremel type drill so i could try to cut one of the larger sizes that are hardly likely to be used..

mattinker · « **Reply #4 on:** June 04, 2014, 09:25:43 PM »

Cutting wouldn't be a problem with a 1.6mm disk on a 115 or 125mm Ø angle grinder. You might want a thinner slot, but there is no reason why it shouldn't work.

Regards, Matthew

Chuck in E. TN · « **Reply #5 on:** June 05, 2014, 07:23:08 AM »

I'e cut HSS tool lathe bits with a Dremel tool and reinforced cutoff disks. Should work for the die, but I don't know about drilling and tapping for an adjustment screw.
Chuck

awemawson · « **Reply #6 on:** June 05, 2014, 07:56:08 AM »

The adjusting screw would be in the holder, which is unlikely to be hard

mattinker · « **Reply #7 on:** June 05, 2014, 07:57:10 AM »

You don't need to drill and tap for an adjuster screw. You need a pointed grub-screw to screw into the newly cut slot ( "V" the slot to provide a surface for the pointed grub screw to push on) that will open the tap. Two grub-screws into the dimples (drill tap and thread die stock [the handle] if absent) will close the die.

Regards, Matthew.

Fergus OMore · « **Reply #8 on:** June 05, 2014, 08:18:45 AM »

I think that you may be mislead. It's all good advice but the notch in the unsplit die is simply to hold the die from rotating. What you have bought is actually for re-threading a worn male thread rather than to cut a new one. With a bit of careful grinding, you can make it into a split die by cutting through where the notch is now. However, there is a catch- the die has no lead( pronounced leed) and you still may have trouble commencing the start of the tapping operation.

What you need is to make a taper lead( leed) into the die with a tapered abrasive point.

If you have followed an earlier posting there was someone who was making one single tap on a lathe- 1/4" x40 tpi - which is actually a measuring tap and is not cut but ground. If you follow the correct description of taps you will find that normally three taps are available. the first is obviously a First lead tap with a long taper and the 2nd cut a wee bit shorter taper and the third a bottoming tap which has virtually no lead. So, if you are still with me- you have something akin to a bottoming die. It is not called that but that is what it is for.

Again, you have a 1/2" die and to use it without needing to be an Olympic athlete to add this necessary taper to your die.

Does this help?

Norman

stirling lad · « **Reply #9 on:** June 05, 2014, 08:47:39 AM »

thanks guys for all your help,,

Chuck, i've got a couple of the dies your talking about with the screw actually in the die split but most of my other ones just push a pointed screw into the split to open it up a little..
So is the consensus this; splitting this die would probably work in theory but that it's not meant to be split and the slot is just to stop it turning,,plus the tapered start is'nt enough for starting a cut,??mmmm, so why the 2 extra dimples just where you'd put them to close a die? ..

life would be so much easier if the lottery would hurry up and give me my turn at being loaded

then i would'nt have to faff about with dodgy tools in the first place...

mike..

BaronJ · « **Reply #10 on:** June 05, 2014, 09:19:53 AM »

Hi Guys,

I think you may find that the notch and dimples are used during the manufacturing process to secure the die blank in forming and grinding stages. Simply a convenience that they are there.

vtsteam · « **Reply #11 on:** June 05, 2014, 11:31:22 AM »

Having seen the second photo now, I'm voting or Fergus opinion that it's thread chaser since it seems to lack taper. It looks like there's a little relief on one side to start without cross threading, but no taper.

Arbalist · « **Reply #12 on:** June 05, 2014, 11:33:24 AM »

I've got a couple of solid dies that have leads on them for cutting new threads so it's not just split dies that have them. One of my best dies was a solid M6 encapsulated into a plastic handle with a guide bush. Sadly I broke the handle in a senior moment... I still have an M4 combined die and stock somewhere that I bought from Buck & Hickman.

Fergus OMore · « **Reply #13 on:** June 05, 2014, 12:13:05 PM »

Actually, a die with two dimples and a slit are intended to hold the die with the two dimples and for the slight- and I mean slight opening of ONE of the holes to do the first -or initial cut and then when reversing back, to release the pressure to cut a gnat's cock more. Obviously, this initial cut puts the whole thing out of square or round but is properly formed -going back out.

I have to point out that quite a lot of cheap taps and dies have no leads to speak about. This is where one has a tool and cutter grinder- however crude- to grind the tapers on the leads of the cheap taps- or sharpens the blunted ones. One of my old diseased mates used to put the edges back on the leads of his taps with a triangular hand stone. Me, Oh Hell, I've sort ignored the so called advice of lots of experts( in their opinion) and I made up diamond dresser to shape the grinding edges of some of my wheels. If your inverted rear parting tooling has a 140 degree 'female' vee along the cutting edge, I don't know any other solution.

Regards

Norman

Houtenkrullen · « **Reply #14 on:** June 05, 2014, 05:46:15 PM »

Hello everyone,
If I may add nu two cents...
I live in the Netherlands, and haven't seen a split die in all my life. Have read about them though.
Over here all regular dies (as far as I know) are of the type as discussed. We have dies with hex exteriors for rethreading damaged threads, although I haven't seen many of those. Most people use a regular die for rethreading (including myself. If anyone knows a reason not to, please let me know) All my dies have all the holes yours have. And all my holders have screws for all the holes (which I find a bit peculiar)
I can't say for sure that yours are the same kind, but you might just give it a try. Maybe you ended up with a "continental set", but it might just work fine as is.
Cheers,
Peter

Houtenkrullen · « **Reply #15 on:** June 05, 2014, 05:50:39 PM »

P.s. There should be at least some taper on the side of the die with the brand an size markings if yours are like mine. Looking at your pictures there seems to be some??

Stilldrillin · « **Reply #16 on:** June 05, 2014, 05:52:23 PM »

Mike.
To me...... Those look like split dies. Without the splits.

Guess the manufacturers add a split, or not. Depending on customer preference......

David D

stirling lad · « **Reply #17 on:** June 05, 2014, 09:11:33 PM »

Thank you Peter,

I was beginning to think that maybe reading about these dies on the continent had just been a dream

,It's nice to know that it's true and split dies are'nt readily available...but why it's like that,,I have no idea...The photos don't really show the taper too well, but it is quiet deep,,As good, if not better than the old BA dies I have but then maybe their worn down...
David,, that's what I thought at first but now i'm more confused than ever albeit with a lot more possibilities ...

..
I think it's time for some experiment's...

...

... thanks again Modder think tank...

...mike...

Jonny · « **Reply #18 on:** June 06, 2014, 10:34:01 AM »

Its the other way round for most rarely do we ever see a rethreading die.

Do have one decent Goliath M8 course split die brand new pre 94 boxed and does have the hex outer for spanner work.
The first set of taps and dies came from local motor factors, cheap and nasty carbon most broke with no effort but were all rethreading dies.

Think what this boils down to is where you do your shopping. If shop at car/diy place expect rethreading die, if shop at a reputable engineering supplies expect a proper split die where rethreading dies could be supplied to order.
Even ebay worldwide its harder to find rethreading dies, split are the norm.

As regards the two indents Normans 100% that's how to adjust the size the die cuts and to stop die slipping, no other purpose.
Between the two indents if you like theres a centre which will expand the die up when driven in.
Self explanatory

Henning · « **Reply #19 on:** July 10, 2014, 09:11:47 AM »

Highly interesting thread.

Now, before I start; I've been working with toolsales ever since I left the army, before that i was trained as a gunsmith (which I also worked as in the Norwegian army). I have exclusively worked with pro industry customers now for 15 years for the largest tool distributor in Norway with some of the largest European tool brands.
That aside, i think there's some pretty basic differences between continental Europe and GB and the USA.
I have never seen a split die, but vaguely remember them beeing briefly discussed during my years in school.
As others have mentioned, here and in other places continental europe the die in question would be a standard threading die. MOST of those have a lead in taper on the side with the manufacturer markings (But can be ordered with minimum or no taper for special applications). One example of such a die which produce a finished thread may be found at the top (and onwards) here: http://www.dormertools.com/en-gb/products/pages/ProductSearch.aspx?primarycategoryid=dies
Now, a cleanup die would in MOST cases be hex like this: http://uk.farnell.com/dormer/f302m16/hexagon-die-nut-hss-16-x-2mm-metric/dp/1477492

All the holes, and also the portion which you wanted to cut Myfordlad, on a die has a corresponding screw on the dieholder which locks the die into the holder. One example of such a dieholder is here: http://shop.stianmotorsport.com/produkt/10421786/gjengebakke-38x14mm-m12-m14

This regular type of die cuts a fully finished threadform, but you cannot but trust the manufacturer when it comes to finished sizes. I've been looking for a set of split Metric dies to be able to adjust the fit a little better, but for regular use those dies work fine if you choose reputable manufacturers.

Now there's also one manufacturer still producing square dies and relevant tooling, which is slightly different but most of the same applies.

Please note i have used random pic's and links off of the internet to avoid someone taking this for something it aint. I have no connection to any of the products, manufacturers or otherwise which i've linked to.

Hope this helps some.

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Author Topic: a question about dies (Read 9163 times)