threading question

[mike thomas]

If one is external threading at an angle different than 60, does one change the setting of the compound infeed from 29.5. How is this setting arrived at, and what would be the optimum infeed angle for a 55 degree thread. Thanks, Mike

[Ron LaDow]

Mike,
The 29.5* setting is to make sure that nearly all of the cutting is done on one side of the cutter, with just a 'skim' on the other side.
For a 55* thread, the same rule would apply, half the included angle minus a touch, so half is 27.5*, make it 27*. Obviously, the tool needs to be ground to the 55* total angle.
BTW, what sort of thread is 55*?
Ron LaDow

[mike thomas]

Ron, That is what I figured, I just wanted another opinion prior to running the bit in. I have been know to outsmart myself in the past. It is a Mauser receiver. It is common to just run the barrel threads at 60* and live with the slop, but I wanted to do it right. I picked up a 55* center gage from Starrett. Thanks, Mike

[artificer in metal]

The 55 degree thread sounds like a British Witworth thread form.

[Randy]

Yes, British Standard Whitworth threads are 55*. I believe it's pretty much obsolete now. Also, some Italian bicycle components have 55* threads. There are three sets of "standard" for threads in the bicycle industry. British (probably the most common) which is all inch, French is metric of course, and Italian, in which diameters are in mm and pitches are in TPI! Go figure.

[halfnut]

Yes, the 29.5 degrees is for a skim cut on one side of tool, taking most of cut with other side, chip curls out better that way. Yes 27 or 26.5 should work nicely. I do 29 degrees, not 29.5 myself, works fine.

Them englishmen, got them away from the whitworth threads with the unified standard threads, I have a BSA motorcycle which has mostly unified threads. It does have a few whitworths lurking here and there.

I've heard tell that when they adopted the metric system they went back to the whitworth thread form of 55 degrees for their metric bolts. Or so I have heard. My newer machineries is at work, I'd look it up, not in my 15th here at home.

[halfnut]

Looked at original post, Mike, are you sure it is 55 degree thread, got my copy of Gunsmithing out by R Dunlap. He doesn't specify just says vee thread. He also warns that these threads vary sometimes from one to another. Only time I have ever cut threads for a Mauser was on a Siamese Mauser that a friend of mine converted over to 45-70. I cut at 60, maybe it should have been 55.

I'll have to ask my friend Scotty about this one, he's a German relic enthusiast, mostly Lugers. Have a couple 3 around here, don't even want to unscrew the barrel to have a look.

[Ron LaDow]

Halfnut,
Racers get to deal with BSP tubing threads. The hexes are Whitworth, which means a 1/4" nominal is about 7/16". They're commonly refered to as British Stupid Parts.
Ron LaDow

[docn8as]

Halfnut ,et al the last 1/2dozen military mausers i have rebarelled were 55deg.whitworth looking threads....have cut both 55deg & 60 when couldnt find thrd bit /too rushed/lazy to grind another....felt better abt 55's but dont think any practical difference.....thrd must be easy enuf to allow barrel to register properly.........a lot of smiths in 60's cut 12 pitch 60's rather than metric thrd 55's ...12 pitch is 2 1/8 mmm .083333 & if i emember right, military mausers are 2mm. pitch .078
best wishes
docn8as

[docn8as]

mike ...maybe should mention ,98's are designed to butt up to INTERNAL shoulder ...because of that ,shd have .001 clearance on front face ......dont forget to allow for .0015 crush when wrenching up( unless u are godzilla ,) .001 is enuf....does not need to be near as tight as the one that came off!....check to see if both lugs bearing evenly, if not get out the valve grinding compound......if u want to get really involved there is trueing up thrds,lug seats ,shldrs,faces....bolt faces
best wishes
docn8as

[halfnut]

Doc,

Yes, something is sticking way in the back of my brain somewheres about this 55 deg thread on the Mausers. Kinda strange, Germans using the Whitworth form, but at that time in history. I looked and looked in this one gunsmithing book, it does mention that threads were probably metric but that a 12 tpi vee was good enough. I've got a 8mm with a new barrel on it that isn't indexed quite right, needs to come apart sometime. I'll have to do some inspecting.

Doc, I noticed that You used the word dotage the other day, not a common word in todays language, wondering where you picked it up at, maybe the same place as I, ssohh.

[mike thomas]

To all, This has been quite a project. Much more than I originally envisioned. I made a mandrel and trued the reciever face, lapped the primary torque shoulder to less than .0003 variance at any points compared to the receiver face. Then I lapped the bolt lugs to about 90% contact, with less than .0003 variance between any points on the bolt face and the primary torque shoulder. Then the thing went off to be reheat treated. So, with the additional thread info, I think that I have the bases covered. Thanks, Mike

[docn8as]

mike makes a commercial bench rest action a lot more interesting doesent it, u havent added in fully adj. trigger yet!!!!.....the truth is , the guys (&WRITERS ) that touted all these military conversions years ago , did almost no action trueing.....mausers arenot that hard & usually everything set back enuf after use to even things out i never saw one w/ less than .011 hdspc(sprgflds went to arsenal@ .010) .AND they thought 1 1/2in groups GOOD when they finished(military spec was abt 3in) around the 50's ,realized they flexed too much & started sleeving them & that was the beginning of accuracy.........one of problems of boards is ,not knowing the depth of exp/knowledge of poster.thereby having redundancy/aggravation directed at respondent.....
i have to hang a little crepe...hope u check those.0003 parameters AFTER heat treat,....& that ur resource has GUN experience.... mauser steels were pretty simple & hardened to abt 28 to 30& u do not want it to turn it into a fragnentation grenade ,like some early sprgflds, enflds,& us krags (norwegians had better steel)i have been on the range when a rcvr let loose ...try shooting a 20 shot offhand match w/ #16 rifle 20 min later!!!!! just nestle into that stock w/the rear of bolt bisecting ur cheekbone!
best wishes
docn8as

[docn8as]

Halfnut,with the increasing temporary memory lapses, & inability to pull a well known name or word out & 15 min later it appears , "dotage" just seemed the most apt....one of the portents of the future is is to attempt to store a new purchase ,picked up in town, only to find , occupying the space ,the same item u purchased last month in town!!!!!.....well ...any day above ground is a good one !........my #62 pointer bred a gypsy lab bitch, ..kept one pup ...he looks like a rangy #85 jet blackpointer w/ star ,5 inches taller than either parent ,15 months old.....took him out & pointed/held 3 birds ,backed & fetched (would rather be lucky than smart)!!!!!!
best wishes
docn8as

[mike thomas]

Doc, May I call you Doc? Yep, I rechecked those spec after heat treating. I used a firm in Salt Lake City that has been retreating Mausers for many years. They went for a .010 case at 28-35. I have no idea what they achieved, but it has a number of indentations where they hardness checked. What I listed in the previous post is only the start of what I have been doing to this beast. It is a VZ24, and I have a 6mm Hart 1-10 barrel in the headstock now. I purchased a Timney featherweight trigger and their copy of the Buhler saftey. I forged the bolt, pear shaped the knob, and then removed most of the backside of the knob. Looks kinda nice. I have done a couple other in this style. I am going to slightly reshape the trigger guard, and blue it and the receiver. The bolt is to be polished and the extractor jeweled. The stock is a classic style laminate.
The Mauser seems just great to learn on. Purchasing a benchrest action would only leave more time for housework. A 700 would be a nice compromise, and if one had to pay for the work, much more economical. In fact, if one sold off the parts not needed from a 700, the cost for a home done Mauser or 700 would be close to the same. Mike

[docn8as]

MIke.......i didnt know that there were any more like u around .... u take me back 40 + yrs..u should have a beautiful rifle + maybe the most important other thing..."i did it my way"... u started w/ fine action, ..i used to use a sprgfld guard(used to be $1.98+ )or else weld up keeper screw holes& shape guard as much like English double shot gun as possible,bolt sounds nice ...i preferred to weld on a brownell that i checkered or else turn a custom one ..liked them a little longer ,swept back... i have a double set trigger around somewhere that i made ,thot that $118 from brownell was too much HA.!..had made them before for ballard sheutzen & forgot how time consuming..i think the ones i made w/ hand tools took abt same time as 30 yrs later w/ mill!!!!....set ups!havnt done much for a long time but still love them.......if u want to talk abt PRACTICAL things in chambering,making hdspc gages , chambering reaqmers,( simpler than u might think) center reamers ,loading dies chekering, stocking from blanks ,let me know .best wishes
docn8as

[halfnut]

Doc,

I was just curious about that particular word usage, we are all getting to that point. Thought you might have picked it up in a certain particular place, and not a bad place either.

Sounds like quite a dog, hybrid vigor.

Bad thing about pure bred dogs, they don't live that long sometimes, get a mutt and you have to feed them for purt near 20 years. As a kid we had 2 collie, sheperd mixes that lived to be 16 or 17. My mutt dog is mixed up even more, she'll probably make it to 20, she's not good for much, hell on Possums though.

Doc, take care, write notes, I do that sometimes, then I wonder what the notes about. It will be terrible when I get older judging by the way I am now at 39. Young pup, right.

[Thrud]

Gents,

55* threads are still the defactor standard in dealing with English goodies. Metric system bad - Whitworth Good! (NO IT IS NOT - GO METRIC) Thus I labour with Whitworth threading on my Stuart Turner engine kits (must use the Whitworth SCALE hardware you know). I hate buying whitworth taps & dies, but it IS THE MOST DIFFICULT WAY KNOWN TO MAN TO DO IT. So I put up with all this "scale" crap. I am told they even want you to use the "Approved" colours in painting it. I digress....

Dave

[artificer in metal]

Borrowed a book from a fellow student when I was in my apprenticeship training on metallurgy and racing cars. (I wanted the metallurgy!!) In it was explained why the 55 degree threadform should be used rather than the 60 degree. The 55 degree form is a much stronger cut form - now when threads are rolled I think it would still be true but possibly not to such a larg extent. Noticing that you were using this thread form for gun parts I would think that the strength of the thread is of MAJOR importance - therefore the 55 degrees IMHO.

Interesting reading this BBS!!

[SGW]

Isn't the small stuff on Stuart kits BA, not Whitworth? BA is something else entirely! 49 1/2 degrees, I think....

[mike thomas]

I cut the threads at 55* with the compound set at 27* and she clunks home solid. Thanks, Mike

[Thrud]

SGW

Sure, remind of that now (that is why I like the 60* UNF, UNC, & UNS - one stinkin' angle fer me brain to explode on!) - explains why one part don't fit...

Thanks, I needed that

Dave

[SGW]

I've built one S-T engine, and I used the supplied BA fastenings. If I ever do another one, I'll convert to NF threads (NF comes out closer to "scale" than NC) and make the fasteners.

I think the most important thing to scale though is the bolt and nut head sizes.


[This message has been edited by SGW (edited 11-20-2001).]

[Thrud]

SGW,

I would prefer to do that, but the agent I bought the kit from (an estate offering) is giving me a hard time about doing it the "English" way. He tells me the kit is an original 7A and no longer available - more the reason to do it the "right" way I suppose.

The old fella that originally bought the kit screwed up the parts he started on. I had to get new reversing gear castings, flywheel, and have not yet fabricated a respectable looking crank. I want to go for the "forged" look that MEW showed a while back using silver steel (drill rod) and grinding it to that "rounded" look.

Dave

[wulfesinger67]

Halfnut i dont know much about the british threads but i am familiar wth the term dottage maybe we run in te same circles?you might know a friend of mine names Hiram?



<font face="Verdana, Arial" size="2">Originally posted by halfnut:
Doc,

Yes, something is sticking way in the back of my brain somewheres about this 55 deg thread on the Mausers. Kinda strange, Germans using the Whitworth form, but at that time in history. I looked and looked in this one gunsmithing book, it does mention that threads were probably metric but that a 12 tpi vee was good enough. I've got a 8mm with a new barrel on it that isn't indexed quite right, needs to come apart sometime. I'll have to do some inspecting.

Doc, I noticed that You used the word dotage the other day, not a common word in todays language, wondering where you picked it up at, maybe the same place as I, ssohh.</font>

[halfnut]

W,

Yes, I've met him. It might be interesting to know how many others might have also ran across this fellow. I'm in the east this year, a privelege and an honor, I hope I do the station justice.

Pittsburg, a whole 25-30 miles from Jasper. Did I meet you at Webb City this year at GW days, Pittsburg bunch was there for the 3rd.

H Sprenkle

[This message has been edited by halfnut (edited 12-10-2001).]

[kap pullen]

doc,
I have acouple of them wwi american made enfields,one in 303, and one 30-06.
I was told that was a good action to rebuild into maggies. Is that not so? I knew early springfields were guestionable but not enfields. I'll have to retire them .
That 303 is so sweet and accurate one of my favorites.

Kapullen

[wulfesinger67]

well met bro&gt; i to am in the east again (3rd time in as many years)
as well as ending my term as ddgm....no i wasnt at webb city im master at cherokee lodge but i live in pitt.unfortunatly tues my lodge is voting to consolidate but i think in the long run it will be a bonus.I ment to get over to lamer this year but had to much n my plate. do you know of any model engineering clubs in this area?



<font face="Verdana, Arial" size="2">Originally posted by halfnut:
W,

Yes, I've met him. It might be interesting to know how many others might have also ran across this fellow. I'm in the east this year, a privelege and an honor, I hope I do the station justice.

Pittsburg, a whole 25-30 miles from Jasper. Did I meet you at Webb City this year at GW days, Pittsburg bunch was there for the 3rd.

H Sprenkle

[This message has been edited by halfnut (edited 12-10-2001).]</font>