Thread chasers

[Speedy Builder5Participant @speedybuilder5]

Where do we go to buy 40 and 32 tpi Whit/ ME thread chasers. I have seen some very expensive ones, and bought some very cheap ones, but never the ones you really need.

[Speedy Builder5Participant @speedybuilder5]

Where to buy at low cost

[JasonBModerator @jasonb]

Tracy tools do a holder so you can use a single coventry die head bits. Tehy also do other chasers

 

Jason

[chris stephensParticipant @chrisstephens63393]

Hi Robert,

As Jason says the Tracy tool set has a good number of chasers in a set but i cannot remember if they have those sizes. Last year at Sandown Tracy tools quite generously donated a set to us at SMEE, so I gave an impromptu demonstration and even got to show the chap from Tracy tools how they were used to cut threads. I always feel it helps to sell something if you know how to use it.

chriStephens

[Chris TriceParticipant @christrice43267]

I use chasers all the time to cut or finesse external threads. They can be clamped in a tool post like any other lathe tool. All of mine came second hand from Home And Workshop Machinery in Sidcup. They advertise in the MEW magazine and they’re regulars at most of the model engineering shows. Although I have a few internal chasers, I tend to use a tap mounted like a boring tool for machining internal threads.

Edited By Chris Trice on 21/06/2011 02:27:52

[JasonBModerator @jasonb]

Tracy do a set with so 40 & 32 included. Here

[Speedy Builder5Participant @speedybuilder5]

Thanks for advice – still looking as Tracy only advertise BA and H&WM don’t have any at present. Surprised as there are loads of ME drawings out there with ME and Brass threads – expensive to keep buying dies, and loath to smash a new die just to make a chaser. I keep an Eye on E-bay, plenty of metric and Unified, – not so many small Whitworth form. Even buying a couple of diehead chaser sets would be expensive.

 

I bought a bucket of chasers from a private collector, but most of the useful ones were missing – still, the price was good. I suppose I should put an item on the wanted list.

[chris stephensParticipant @chrisstephens63393]

Hi Robert,

If you go back to the Tracy tool page and look at the bit that seems to indicate only BA and click on the little arrow, you will see two more options one of which lists 12-40TPI chasers.

chriStephens

[NJHParticipant @njh]

Hi Robert

 

I bought a set from Tracy at last years Bristol show they comprise:-

40,32, 28, 26,24,22,20,18,16,14,12 Whitworth form.

 

Sorry to say I haven’t used them yet but my current projects will soon need some screw threads. ( Thats if I don’t screw them up first!!)

 

Regards

 

Norman

[Speedy Builder5Participant @speedybuilder5]

Tracy tools have been helpfull as I did not see that there are 3 different sets available using their web drop down menue. The third set is as follows, and I posed the following question to Tracy tools:

Please could you tell me if the 20,22,24 ….56,60,72 range of chasers are whitworth ie ME and Brass profile,

Tracy tools reply:-

To be honest it’s really a mixture of UNS and WHIT FORM, the coarser threads tend to be whit but as you get up to the 48 and higher it’s mostly UNS, I checked the 32 and 40 tpi and they are both whit form.
(Oh, and those of us that don’t know, UNS are Unified form 60 degree thread angle)

 

This suits my purposes, and a such, I am closing this thread.

 

Bob

[Ray Pope 1Participant @raypope1]

Does anyone know where I can buy/acquire a BSB (26 tpi) external thread chaser. Application is for male and female 7/8" BSB threads. Would buy used taps and die if available. Have a 7/8" no.1 tap. Thanks in advance.

Ray Pope

[DC31kParticipant @dc31k]

Posted by Ray Pope 1 on 11/04/2023 21:56:04:

Does anyone know where I can buy/acquire a BSB (26 tpi) external thread chaser.

Use a 1/4" BSF Coventry die chaser held in a pair of mole grips. Pitch and form are correct.

Coventry Die Head Chasers Imperial BSF

[JasonBModerator @jasonb]

12years on and Tracey tools still do the chasers including 26tpi

[john halfpennyParticipant @johnhalfpenny52803]

A lot of ebay chasers do not specify the die head size, and are thus not likely to sell (at least to me). Some time ago a very helpful comparative photo was posted on this forum of most sizes, but that doesn’t help identification because they all have the same appearance. It occurs to me that thickness may be a differentiator, but forum searching hasn’t confirmed this . Chasers for a 5/16 head are 5/32 (0.0156) thick.

Perhaps someone would post thicknesses for 1/4 and 3/8 die heads. I know this is all ancient history, but the Coventry die head is useful to me.

 

 

 

 

[Andrew CrowParticipant @andrewcrow91475]

Hi John, I’m afraid that thickness of the dies won’t help much as 1/4 dies are also 5/32 thick and 3/8 dies are 1/4 thick the same as 1/2 ones. The only thing I can say is that although the same thickness they are somewhat smaller in overall size. So if you were to put a set of 3/8 x 20 dies in an 1/2 inch die head it would cut a 1/2 inch x 20 thread.

Andy

[David SeniorParticipant @davidsenior29320]

My notes suggest the sizes are as follows:

1/4″ die – 0.312″ x 0.157″ x 0.625″

5/16″ die – 0.439″ x 0.157″ x 0.661″

1/2″ die – 0.5″ x 0.25″ x 0.844″

Sorry, I don’t have a 3/8″ die.

I guess the last dimension for each could vary depending on the grind?

Dave

[Charles LamontParticipant @charleslamont71117]

Quite a while ago I was able to built up a set of second-hand Whitworth-form hand chasers from Tracy Tools, as and when they had them available. I chop the tang off and use as a machine chaser for finishing.

[john halfpennyParticipant @johnhalfpenny52803]

Many thanks both. Useful information nevertheless. It seems from Dave’s info that width may be a differentiator for the smallest sizes – so that is helpful

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