The Forestry Forum

General Forestry => Sawmills and Milling => Topic started by: tbish on January 14, 2020, 07:11:54 PM

Title: Mandrel nut
Post by: tbish on January 14, 2020, 07:11:54 PM
Where can I buy a mandrel nut saving a circle mill nut was toast beyond use thread measurements 1 11/16 od to od of threads and hello everyone  mill is old geiser made late 1800s
Title: Re: Mandrel nut
Post by: moodnacreek on January 14, 2020, 08:08:19 PM
An industrial supply house.
Title: Re: Mandrel nut
Post by: Oliver05262 on January 14, 2020, 09:49:23 PM
That seems like a one-off thread if it was measured correctly. That old, it's not likely to be metric. :) The pitch (threads per inch) is the other really important part of measuring that nut and shaft. You might have to have a nut custom made and the profile might not be a standard shape either. How much is left of the old nut? Save it for sure, because it might help a machinist create a new nut for you.
I found this; it might help a bit.http://vintagemachinery.org/mfgindex/imagedetail.aspx?id=509 (http://vintagemachinery.org/mfgindex/imagedetail.aspx?id=509).
Title: Re: Mandrel nut
Post by: Dan_Shade on January 14, 2020, 09:52:20 PM
You might be able to wax it really well and cast some bondo or plaster to get a mold of the threads that a machinist could use to make one. 

Title: Re: Mandrel nut
Post by: Gearbox on January 14, 2020, 10:01:02 PM
Is just chewed up from a pipe wrench ?. What is wrong with it ?
Title: Re: Mandrel nut
Post by: tbish on January 14, 2020, 10:51:02 PM
Its looks like someone used cold chisel on it I'd be scared to use inside threads are ok thought somebody might no who sells mandrel  nuts thanks guys want much turning up on my searches
Title: Re: Mandrel nut
Post by: moodnacreek on January 15, 2020, 07:59:46 AM
That nut would have to be cast iron. On machinery that old I have found nuts, bolts and even shafts that where not steel.   If the threads are still good on that nut I would consider turning it round [od] to a size that can be bored in a steel plate/block to put a shoulder/ ring around it. This could be beveled and brazed on. Worst case make it square for wrench.
Title: Re: Mandrel nut
Post by: sealark37 on January 15, 2020, 10:31:42 AM
The key to your problem with the nut is the mandrel shaft itself.  The threads on the mandrel need to be measured for Outside Diameter, as well as Pitch (threads per inch).  The thread type, or profile, also should be noted.  With this information, a new nut can be made.  The ideal would be to take the mandrel to the machine shop, so it could be matched precisely.  You are not likely to find this nut in the hardware bin at the local hardware store.   Regards, Clark
Title: Re: Mandrel nut
Post by: Ron Wenrich on January 15, 2020, 11:30:17 AM
If the inside threads are ok, then I'd take it to a machine shop and have them make a copy.  Its not like you lost the nut.  
Title: Re: Mandrel nut
Post by: luap on January 15, 2020, 02:47:21 PM
As a machinist I have done this type of job several times. With the old nut in hand I would cut new threads on a shaft to fit the nut and then use that threaded shaft  to be my go-nogo fit for the new nut. I did not need to have the existing shaft. Not a hard job with a good lathe and a mill to cut new flats on the nut.  You just need to find a small shop with someone that can do that. It may be possible that a tap exists of the correct size and pitch That  could be used to make a new nut. Did you measure the od of the shaft at the shoulder where there are no threads but still the same size as the od of the threaded portion? A machinist can get everything he needs to know from the existing nut.
Title: Re: Mandrel nut
Post by: luap on January 16, 2020, 01:21:12 PM
Out of curiosity I looked 1-11/16 up in a thread chart and it is listed in a 16tpi and 18tpi. 

   http://server2.smithy.com/media/pdf/Standard%20Series%20Limits%20Size-Unified%20and%20American%20Screw%20Threads.pdf
Title: Re: Mandrel nut
Post by: sharp edge on January 16, 2020, 02:10:46 PM
As a machinist I would like the shaft, skin cut the threads and face the collar, then make the nut. The rest of the mill must be all wood. ???

SE
Title: Re: Mandrel nut
Post by: tbish on January 16, 2020, 05:32:30 PM
Measured the threads it is 5 tpi shoulder measures 2in got ahold of d@d sawmill supplies got to get back with them with measurements 
Title: Re: Mandrel nut
Post by: Al_Smith on January 16, 2020, 07:19:19 PM
It's not difficult to make a nut ,I've made a few and now a story .Repairing a milling machine vise that needed a nut I made the nicest brass nut ,4 TPI ,acme thread .It was a beauty,took me an hour  except it was a right hand nut and needed to be a left hand nut .So I got to make one of those also .It helps to pay attention .  ::)
Title: Re: Mandrel nut
Post by: luap on January 16, 2020, 07:30:44 PM
It would be nice to know exactly how you are measuring the threads and have the measurements to the thousands of an inch. As Se said he would like to have the shaft which gives the opportunity to use a micrometer and a wire gauge set to measure with. If you measure across the thread you have the crest of the thread on one side and the bottom of the thread on the other. If you measure the crests across from each other it will be at an angle. If you hold a scale on the end of the end of the shaft your eye cannot detect the taper at the end of the thread. Plus that size thread is cut undersize by .010 for clearance. 5tpi is common on 1 3/4 thread.  Not saying you did it wrong but I don't know  from the remote perspective of a computer screen. Fastenal is a great source for anything threaded.
Title: Re: Mandrel nut
Post by: Al_Smith on January 16, 2020, 08:34:03 PM
FWIW a grade 5 1 3/4" nut is about 8 dollars a pop ,McMaster -Carr.
Title: Re: Mandrel nut
Post by: luap on January 17, 2020, 01:05:13 PM
If the crests of the thread has been flattened your measurement of the od of the thread is probably correct but the 5tpi leads me to believe it could be 1 3/4.
Title: Re: Mandrel nut
Post by: tbish on January 17, 2020, 07:46:36 PM
You could be correct on 1 3/4, I'm just using a  tape measure?? I may buy a 1 3/4 give it try not that expensive, before i go to machine shop thanks guys
Title: Re: Mandrel nut
Post by: Al_Smith on January 17, 2020, 10:13:10 PM
It would not be unusual for the portion of the shaft exposed to weather would rust to the point it would be difficult to get the exact measurement .Never seeze  that new  nut if it works .You might want to get it off again .That stuff works but you have to use it prior to not after the fact .I've fought rusty old stuff since I was knee high to a  grass hopper .Been there and done that .  ;)