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Member postings for Russ Bulley

Here is a list of all the postings Russ Bulley has made in our forums. Click on a thread name to jump to the thread.

Thread: Drilling and tapping hard material
05/08/2020 10:46:58

M6. Great link thanks!

Edited By Russ Bulley on 05/08/2020 10:48:35

05/08/2020 07:46:55

I am bushing a small steel casting made in 1929 that is very hard, the steel blunts a HSS drill in an instant. I have broken several taps (by hand) and boring the casting has been a nightmare only solved by using a PCD tipped insert - which then broke! The casting has had a hard life and could have been "work hardened"?

What specialist tap manufacturers are in the UK who can provide specialist taps for very hard materials?

Any tips for tapping, other than winding back regularly and using high quality cutting paste?

Russ

Thread: Threading and the tables
01/04/2020 19:06:04

I want to say thank you to everyone for the contributions above. Very helpful!

Russ

31/03/2020 20:58:38

Clive, no I rarely can as I am using suds and at high speed the overspray is terrific. Anyhow charging (9 tpi remember) into a dead end also scares me. So I was using 5 thou increments to try and compensate.

To SOD good point, but why is the tapping drill size way off the table? I still don’t understand this tolerance as all I want is a standard thread medium fit!

I will measure the tap as suggested.

All good stuff guys. So where do you obtain the true machine use data (I acknowledge SODs comments)?

Russ

Thread: Square thread cutting
31/03/2020 19:38:18

This is a very useful text on square threads https://smithy.com/machining-handbook/chapter-3/page/24

Russ

Thread: Threading and the tables
31/03/2020 19:28:18

So thank you for the replies. Yes always do spring cuts. And as I am using Sandvik inserts, think the form will be correct.

I did also say these particular threads were internal.715ff0aa-196b-44df-8f69-8c56b3147e22.jpeg

4f2e5026-d0d3-42f5-8a84-444aec997ded.jpeg

31/03/2020 12:29:35

I want someone to educate me!

As I have said before, I am not a professional, learning as I go along, and have just finished 8 x 7/8” 9tpi BSW internal threads about 2” long which has taken about three days.

Now my book (British Standards for Workshop Practice - but this seems to apply to all thread forms and tables) says for nuts medium fit, the minor diameter (which I take as h on the diagram) is between 0.7328” and 0.7620” with a tolerance of 0.0292”, depth of thread 0.0711”. So, I bore to 0.740 +/- 0.003” thinking that’s in the tolerance zone, then thread to 0.071” depth, measured with a DTI on the cross slide. But then I test with a tap, and every single thread was really tight and I had a struggle getting the tap down. All are done now, but what am I doing wrong? By the way I am using a BSW insert cutter.

I have to say, even when cutting outside threads, I can never get it right, even though I use a DTI on the cross slide and I have eliminated most wear by adjusting gibs etc. What’s the secret of reading the thread data tables?

Also, if I am using a straight Vee cutter (not a profile insert) the apex of the cutter is actually at H/6 (for BSW) deeper than the bottom of the thread due to the curve. How do you get your depth correct, as you need H/6 + h as a finished height, when you have a tolerance of 0.029”!

Russ

Edited By Russ Bulley on 31/03/2020 12:29:54

Edited By Russ Bulley on 31/03/2020 12:30:16

Thread: Bridgeport micrometer scale screws
17/11/2019 21:31:29

Thanks guys. But importantly the same threads?

russ

Thread: Hi guys just bought a Harrison m300 and looking for info etc
16/11/2019 09:16:23

Already joined! Oundle, Northamptonshire

Thread: Bridgeport micrometer scale screws
16/11/2019 08:18:08

I would appreciate that!

russ

16/11/2019 07:15:50

Thanks for the reply. Here Bridgeport they have separate part numbers?

Thread: Hi guys just bought a Harrison m300 and looking for info etc
16/11/2019 07:12:54

Private message sent. I also have M300 with all sorts of issues...

Russ

15/11/2019 19:47:12

Andrew, do you have a travelling steady?

Russ

Thread: Bridgeport micrometer scale screws
15/11/2019 19:42:38

My J head had the screws missing, so I have ordered and received 6-32 screws. But on receipt the top one is fine, but the bottom one only goes in one turn indicating a different thread, which is odd. Any knowledgable people know the answer?

russ

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