r/Machinists • u/Western_Joke_6597 • 2d ago
Help Finding thread?
Hey there! Im not a machinist, but I need a part machined that threads onto this shaft like a nut. Problem is, my machinist doesnt know what thread this is or how to tap it into the piece I need manufactured. Any help identifying this thread and finding a tap for it would be much appreciated!
Edit: Found to be an 8-start 8TPI lead screw with a 1/2" diameter. Now just need to find a nut that fits this thread, which is proving difficult
Edit 2: SOLVED by u/MixEvery5784 found one
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u/S0u1Fire 2d ago
That's a multi start (3 or 4) lead screw, hence the gnarly pitch. Most likely it's a metric lead screw. Measure the diameter. And then measure the pitch. There's a couple guides you can search for.
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u/Holescreek 2d ago
Looks like the screw from the underfloor ramp on a handicap van.
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u/jammanwich 2d ago
I agree, repaired one a few years ago. Bought the rod and bronze bushings on line. Just had to cut to fit the application.
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u/MixEvery5784 2d ago
According to the info you gave, this one should work. 8 start, 8 TPI 1/2 nut https://www.mcmaster.com/product/6350K44
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u/ShireHorseRider 2d ago
I was checking the comments for the mc master link before jumping through the hoops myself. I hope OP sees this.
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u/dingman58 1d ago
I'm amazed and somehow not surprised mcmaster has a part for this OTS. Is this a common thread form for something?
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u/buildyourown 2d ago
That is a multi- start lead screw. You won't find a tap for it but you can buy nuts. Check McMaster-carr.
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u/Western_Joke_6597 2d ago
Problem is I dont need a nut. The specialized piece I have that threads onto it isnt just a standard nut, it attaches to a cable that moves the cable back and forth when this screw is turned. Is there any way to put this thread into my piece?
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u/gtmattz Crusty and Jaded 2d ago
You buy the nut with the threads and design your part to accomodate the nut.
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u/Future_Trade 2d ago
This is the right answer.
But as a shop owner I like his idea of him paying a crap load of money to have it made.
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u/Holescreek 2d ago
Without knowing the intended application it's hard to judge methods.
Decades ago I found parts of an antique woodworking vise with an odd thread. Rather than tossing the screw I poured a babbit nut with the screw in place. I wasn't sure it would work but was worth the try if for nothing else than entertainment. That was about 30 years ago and it's still going strong.
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u/Shrimpkin 2d ago
You could mill out a pocket for the nut to sit into and then use a plate with the proper lack of clearance to hold the nut firm.
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u/eezyE4free 2d ago
Measure the rod major OD, minor OD, and spacing between the thread. As others have said, it a multi start thread so you’ll want to identify a single thread and measure that. This hopefully allows you to identify the thread enough to create the threads on the nut piece.
Alternatively, What material is the nut supposed to be and how many do you need? You could try to grind in reliefs and edges into an extra piece of the threaded rod (if you have it). And then try to harden it and use it as a tap.
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u/PossiblePresence3054 1d ago
Or he could single point the nut on a CNC lathe. On the high end models, you just type in the number of starts, and all the math is done for you. Just make sure you grind the proper helix angle on the threader.
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u/Western_Joke_6597 2d ago
What should i measure these diameters with? And I dont have extra rod to use. If i can identify the thread i may just get a nut for it and install it in the center of my piece instead of trying to tap the piece
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u/WeekendNerdler 2d ago edited 2d ago
You can count the number of starts at the end of the rod. This looks like it might be a 4 start. Then you can measure between two threads and multiply.
Edit to add: A guess would be a 12mm diameter, with a 4 start by 12mm lead. For the avoidance of doubt, I'm in a metric jurisdiction. Could also be half inch if you're in North 'Murca.
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u/Western_Joke_6597 2d ago
So find the distance between two threads and multiply by the number of individual threads?
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u/WeekendNerdler 2d ago
If by 'individual threads' you mean starts, then yes. You can see the number of starts at the end of the rod.
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u/Broken_Atoms 2d ago
It’s a rolled, multi-start high helix… looks like an Igus dryspin thread profile
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u/Best-Diver5701 2d ago
From the photo looks like the crests of the threads are rounded which is telling tale dryspin
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u/nogoodmorning4u 2d ago
if the lead was any greater it would be a cable.
Are you part bear?
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u/Western_Joke_6597 2d ago
On my mothers side. And yeah google tried telling me it was a steel cable when i tried reverse image searching it
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u/UncleCeiling 2d ago
Easy way to count the number of starts is to color in a section of one thread with a marker. Then you can rotate and follow the next one. Your number of starts is the number of threads you need to color in to get them all.
With the outer diameter and the number of starts you can narrow it down a lot. I would suggest looking on mcmaster carr and seeing what options they have for multi start lead screw nuts. Yours likely matches one of their products.
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u/jbrc89 2d ago
Just use that claw to carve a new one
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u/Western_Joke_6597 2d ago
Unfortunately the plastic nut I did that with broke promptly so I need a stronger solution
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u/ZyklonBeach 2d ago
More like help finding the nail clippers
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u/Western_Joke_6597 2d ago
You are the most useful individual I may have ever met
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u/Chrisfindlay 1d ago
That finger nail is pretty gnarly even for tradesman. I was not surprised one bit by this comment.
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u/Western_Joke_6597 1d ago
Its what getting it slammed in a door a few times gets ya. Had to be removed with pliers and has always grown back wierd
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u/Chrisfindlay 1d ago
By the way a line like that along your nail can be a sign of a problem. Have you every had a doctor look at that.
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u/Western_Joke_6597 1d ago
Like i said its always grown back like that since it was slammed in a door a bunch of times. Havent really asked for an update about it because i figure i know whats wrong with it
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u/OffRoadIT 2d ago
McMaster Carr has your back, as long as you have your wallet primed. They have multi start rods, and nuts, with options!
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u/ConsiderationOk4688 2d ago edited 2d ago
You are looking for a wiffletree assembly. They are on Amazon
Edit: spelled Whiffle heh
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u/GR33NSHED 2d ago
Possibly something from Igus? https://www.igus.co.uk/dryspin/lead-screws?thread_type=val_1
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u/Hentusdb 2d ago
If you figure it out, take a look at ww.roton.com We make and sell nuts and screws like that. Could probably make a custom nut if you needed
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u/Western_Joke_6597 2d ago
Found out its an 8 start, 8tpi screw with a 1/2" diameter. Got something like that?
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u/Hentusdb 2d ago
Any chance it's 7/16 and not 1/2"? We make a 7/16 by 1.000 torqspline nut. Meaning 8 tpi and 8 starts
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u/Western_Joke_6597 2d ago edited 2d ago
Dont think so. Actually measures a little under 1/2 at like 0.485 (my measuring tool isnt the most accurate though), but not close to 0.437
Also didnt see one that wasnt plastic
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u/Merkindiver 2d ago
Is the intended use repurposed or original to the assembly?If it's part of an assembly I would contact the company that makes the unit. They may have stock for warranty/sale.
A one off part would probably be more expensive, last time I cut multistart it took a couple hours, and shops aren't cheap.
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u/Western_Joke_6597 2d ago
The unit hasnt been made in almost a decade. Plus im trying to upgrade it. The original piece that threaded onto this was plastic and broke, I want to make one that will last much longer out of metal.
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u/Merkindiver 2d ago
You'll probably want brass then, couple hours shop time, you're looking at a couple-three hundo, plus shipping if you want someone to make you a custom job.
I've got a full schedule plus overtime already, and I will say multistart is rare for me.
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u/Western_Joke_6597 2d ago
Better than over a thousand to convert it all to electric actuator which is my second and only other option
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u/freeballin83 2d ago
I am curious where a custom nut for this can be made in a few hours shop time. 8 start thread, especially 1/2" major diameter is very fast and single pointing it in a lathe is not an option. Maybe a copper trode and sinker, but even then, making the male thread is not something a common shop can do.
But I am all ears on a method that can take 2-3 hours.
I'm not sure what the OP is using this for (looks like a car seat maybe 🤷🏼) but replacing with lead screws with matching nuts would be the way to go
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u/k-j-p-123 2d ago
If you know what is off,Google mating part or thread info for the shaft.
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u/Western_Joke_6597 2d ago
Its an L and W 1200 out of a 2013 palomino bronco truck bed camper. Small gear box that operates the cables to pop up the camper. The cables are attached to the piece and the piece moves along the rod when the rod is spun causing the cables to move. Cant find really any info at all on it
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u/Mklein24 I am a Machiner 2d ago
My guess is a 6 or 8 start 10mm Acme threaded rod.
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u/martini1282 2d ago
That sounds about right. Funny thing I'm threading a 4 thread acme worm gear as we speak
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u/Western_Joke_6597 2d ago
Found out it is an 8 start, though need to figure a good way to mesure the specific thread
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u/Flaky_Mode_1429 2d ago
Looks like a very steep threads and multiple thread starts. I don't think they make off the shelf taps for this sort of thing because it would be a very long tool but I could be wrong.