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Author Topic: Coarse or fine tap and die?  (Read 1223 times)

Denalidave

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Coarse or fine tap and die?
« on: September 01, 2024, 06:56:00 am »
Hi all,
I am going to get a tap and die set. The plan is to use them and as and when its needed replace them over time with individual tools of better quality. I have read bits and pieces on the web regarding coarse/fine and what the differences are for use and the reasons for choosing fine over coarse and vice versa but I am still unsure what would be best to get as a set for model engineering. Fine would be better to deal with vibration? What do you folks buy/use for live steam projects? I have been mulling all this over for ages but I am now in a position to actually buy something!
Thanks
Dave

RedRyder

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Re: Coarse or fine tap and die?
« Reply #1 on: September 01, 2024, 07:13:53 am »
There is also the British BA threads which are excellent for model engineering.

and I believe The British Model Engineer Thread is based on the Whitworth thread with a pitch of 32 and 40 TPI.

Their heads are reduced in size which makes for better scaling.

Stoker

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Re: Coarse or fine tap and die?
« Reply #2 on: September 01, 2024, 01:47:16 pm »
A set may have value for general around the house kinds of things, but for our models I think you may well be better off simply buying the tap or die you need specific to the application and as needed. Most sets end up with only a few of the items ever used, and are generally of inferior quality anyway, unless you are paying eye-popping prices for such a set.
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tenniV11

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Re: Coarse or fine tap and die?
« Reply #3 on: September 01, 2024, 02:02:47 pm »
I prefer BA tap and dies for model steam engines but sometimes I use also metrics.
Best source and good prices for HSS high speed tap and dies:

https://www.tracytools.com/

Fast shipping and top quality
Arnold

krypto31337

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Re: Coarse or fine tap and die?
« Reply #4 on: September 02, 2024, 12:35:25 pm »
Like Stoker said, for model work you are better off buying what you need individually.  When you start a project, buy the taps and dies listed for the build and after a few projects you won't need to buy any more.

The failure mode for a cheap tap is breaking-off in your work which could be catastrophic.  Buy the best taps you can and I recommend the 3 tap set as sometimes the bottoming tap is very handy. My good taps are either Greenfield Tap & Die (now Widia), Presto for BA or any other quality tap from an industrial supplier (not from a big box or hardware store).

For dies the best ones you can adjust with a screw. Accuracy aside, a cheaper die usually won't destroy your work.

My Workshop Blog:  http://doug.sdf.org/

Ironhorse57

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Re: Coarse or fine tap and die?
« Reply #5 on: September 02, 2024, 02:09:49 pm »
Most of my taps & dies have been purchased secondhand, sometime in job lots - always go for decent quality brands though and if you have a lathe then a tailstock die holder is a very useful addition.  Some form of tapping guide is also beneficial

Dave
In a world of small engines every man is a giant

Weedensteam

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Re: Coarse or fine tap and die?
« Reply #6 on: September 03, 2024, 11:41:30 am »
Excellent advice so far, buy as you need them and don't go cheap, if you are working with SAE that is particularly true with 6-32 taps, for some reason they are more prone to breaking than the other sizes.

Many years ago I had a roommate that was really particular about having matched sets of tools and tended to give me a hard time because I had a mixed batch of wrenches etc.
His father was a retired machinist and brought him a box of assorted brands of taps and dies, when he left he handed them to me, saying he would stick with his boxed matched set made offshore. I still have most of the Greenfields and Butterfields 30 years later. :)
Frank C.
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