Approximately 3/4" Major Dia. X 12 TPI X 2" Nuts

Life has been very chaotic and fluid lately, yet I have to replace two very important parts I can not find after months of spare time searching for. I believe I am the third owner of this Brown & Sharpe, Ford being the 1st. I have made 12 TPI bolts before and have never tried internal threads, probably because I don't have that type of measuring tools or knowledge.

This morning I finally found a bolt (From the same machine.) that is exactly alike and an accessible internal thread on the casting base. Looks like I'm not allowed to post images yet...

The Pat. date is 1884 yet probably 110 years old, approx. 3 tons, and a Horizontal Mill. I have it modified to hold a Vertical Mill Head on the back side of the arbor support and can not tighten said cylindrical support.

My guess is to get some 1.25" 1018 Cold Roll Steel Hex Bar and give it my best shot. It has been some time since I've come close to such a machining project. How can I make a device to know when to start slowing down to the right fit with the new found bolt. I have some tools but nothing to check internal equaling external. Maybe a modified ring clip puller with a sliding gauge or do I have to even worry about it and guess between the major and minor at 29.5 degrees with the compound indicator... Then guess more till the bolt fits correctly...

I need some help. The minor on the bolt is rounded. There must be a ingenious practical way to get the right fit for two nuts without testing on the only matching bolt over and over or buying expensive tools.

G2STAR said:

I need some help. The minor on the bolt is rounded. There must be a ingenious practical way to get the right fit for two nuts without testing on the only matching bolt over and over or buying expensive tools.

Click to expand...

sound like 3/4"-12 BSF...that said its two nuts and you have the bolt...it's not like it's going to take forever...git 'er dun.

ps- 4140PH would be a safe bet for material

usually easier to use a nut to test when making a male thread on a lathe. you could use 3 wire method and a micrometer to make a male thread. then the male thread can be used as a screw thread plug gage on a lathe making a nut.
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professionals use a screw plug thread gage GO and NOGO type. cut internal threads til the GO gage screws in. better yet buy a tap. special thread taps easy to get if under 1" dia
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screw thread go and nogo gauge - Google Search

If you are talking about bolts, that go all the way through with head as well as nut accessible, the practical thing to do is to replace them with off-the-shelf modern 3/4-10 or 3/4-16.

If you need a nut to fit an existing hard-to-replace stud, single-point internal threading is not too tough if your tool can go all the way through, which it can if you are making a nut

The longest nut is 2.45". Is the 1018 Cold rolled hard enough to adequately tighten it enough with a M-Head Bridgeport or the horizontal arbor support? What is the least hardest as I'm using a 6" X 3' Atlas.

I would like to know when I'm approaching the internal thread's finished size. Math, Keep checking with the bolt, make a tool, or...? Wires. sounds frustrating to check multiple times.

I thought that tread wasn't made for 75 years?

Also, how does one square off the tool with the inside of the bore? The Hex stock will not be axially aligned from fastening it in the chuck and being able to use the flat as a parallel to the bore.

Aligning the tool is pretty easily, assuming that your lathe has ok accuracy. Get the hex stock as concentric as you can in your chuck. Set your compound angle for threading and then place an indicator stand on one of the ways that your carriage rides on. Install your boring bar relatively straight with the stick out you need for your thread length. Place the indicator tip on the boring bar. Run the carriage back and forth and make tool adjustments until the indicator reads even across the boring bar. Now the boring bar is parallel to the ways (and carriage travel). Assuming the lathe is accurate, your initial drilled hole in the hex stock will be parallel to the ways (assuming the tailstock is aligned) and then your boring and threading will be parallel to the ways. This will be perpendicular to the facing operation you did to the hex stock. Thus your nut will fasten flush onto a stud.

This assumes that your threading tool is perpendicular to the boring bar and each side of the tool was evenly 1/2 your included thread angle (60* 55* whatever). This also assumes that the bore is too small to stick a fishtail gauge in and align the toolbit with the side notch in a fishtail gauge.

To digress further, it is not essential that your bar is parallel to the bore as long as it clears the bore on the full travel. Disregarding error from bar flex etc, the cutting point of your tool will travel parallel to the bore since it is in a fixed relationship to the carriage no matter any angle error in your boring bar. The alignment of the boring bar is a way to align the tip of your threading tool point (in order to cut threads with an even included thread angle—not having leaned over crests or other misshapen-ness)

guessing it was like this? not hex nuts but handles?

4140PH round, thread the internal and weld recreation of the handle on.

blend and done.

Brown & Sharpe Mfg. Co. - 1894 Image-Brown & Sharpe Mfg. Co., #24 Plain Milling Machine | VintageMachinery.org

Post was not applicable but I couldn't delete it,

iwananew10K said:

guessing it was like this? not hex nuts but handles?

4140PH round, thread the internal and weld recreation of the handle on.

blend and done.

Brown & Sharpe Mfg. Co. - 1894 Image-Brown & Sharpe Mfg. Co., #24 Plain Milling Machine | VintageMachinery.org

Click to expand...

NFW, iwananew10K !

I thought about your post for about five minutes and was really liking the idea and it hit me, took me 90 seconds and found the original handles! I have been through a lot, interdisciplinary a good dozen times a day for more than a year. Now I can get along with the very challenging part of this project, I've been really leery of working around it because the vertical mill is balancing there.

Thanks all ! oops

G2STAR: When I want to know that I am approaching the finish size, I leave a small boss on the open end of the thread bore that is about .010" smaller than the finish size of your thread. The boss is only about 1/4" long and bored to the .010" diameter under your desired size. In your case, it is .750", so the little boss is bored to .740". After the job is finished, I just face it off. It takes longer to describe it than to do it. Hope this makes good sense to you. Good luck.

JH

on edit: Once i had a job like this, but couldn't leave a boss in front of the bore, so I epoxied a big washer in front of the hole.
it worked like a charm. When i was done I just knocked the washer off.

James H Clark said:

G2STAR: When I want to know that I am approaching the finish size, I leave a small boss on the open end of the thread bore that is about .010" smaller than the finish size of your thread. The boss is only about 1/4" long and bored to the .010" diameter under your desired size. In your case, it is .750", so the little boss is bored to .740". After the job is finished, I just face it off. It takes longer to describe it than to do it. Hope this makes good sense to you. Good luck.

JH

on edit: Once i had a job like this, but couldn't leave a boss in front of the bore, so I epoxied a big washer in front of the hole.
it worked like a charm. When i was done I just knocked the washer off.

Click to expand...

Thanks James, that is a great way of knowing when getting close to the final pass.

You don't need to fit the thread gauge into the bore. It can be placed on the back side of the part, a chuck jaw, or anything else that's parallel to the ways.

So much for false memories, at least that part is finished. Thanks again.

There's always buying a tap...
3/4 - 12 Special Pitch Plug Tap, High Speed Steel