Looking for Arbor Jamnut

[orren countin]

I damaged threads on the arbor and nut for a Delta Unisaw 36-L552. I purchased the arbor but Delta doesnt know when the jamnut will be available. Could be months.
Its a right hand thread, 5/8 with .9 pitch or 28 TPI. I heard called extra fine thread. Ive been to hardware specialty stores and even 2 mechanical fab places declined. I think because of the finethread combined with 5/8.

Delta shows a A289885 part number. Maybe you know of another maker that uses the same jamnut?.

Any thoughts on how to get one?

[David Buchhauser]

Did you use a thread pitch gauge to measure your threads? If not, then perhaps your measurement of 0.9 mm was off a little bit.
5/8-24 is considered "extra fine" for sae threads. This equates to a thread pitch of 0.041" (1.04mm) as opposed to your measurement of 0.354" (0.9mm). This difference of about 0.005" would be hard to discern using calipers to attempt an accurate measurement of the thread pitch. If your shaft is actually 5/8-24 "extra fine" thread, then a replacement nut is available (in stock) from McMaster-Carr. Price is $15.92 plus shipping. If you need the thinner version, the price is $13.80 plus shipping.
David

https://www.mcmaster.com/91845a345

McMaster exrtra fine pitch hex nut.jpg

https://www.mcmaster.com/95621a600

McMaster exrtra fine pitch hex nut - thin version.jpg

[orren countin]

Did you use a thread pitch gauge to measure your threads? If not, then perhaps your measurement of 0.9 mm was off a little bit.
5/8-24 is considered "extra fine" for sae threads. This equates to a thread pitch of 0.041" (1.04mm) as opposed to your measurement of 0.354" (0.9mm). This difference of about 0.005" would be hard to discern using calipers to attempt an accurate measurement of the thread pitch. If your shaft is actually 5/8-24 "extra fine" thread, then a replacement nut is available (in stock) from McMaster-Carr. Price is $15.92 plus shipping. If you need the thinner version, the price is $13.80 plus shipping.
David

https://www.mcmaster.com/91845a345



https://www.mcmaster.com/95621a600

Hi Dave. Definately possible it was mismeasured. I took the arbor to a machine shop to see if they could repair and the head guy used one of those saw tooth gauges and said it was .9 pitch. I assumed that was mm as if so thats consistent with my estimate of 28 TPI. He could not find a 5/8-28 on his lath tables but said he could play with it to get the right thread. At 90 hour I passed.
I try and get hold of some 5/8-24 nuts and see if they will fit. thanks for the help!

[David Buchhauser]

Hi Orren,
Unless your saw uses metric threads, the guy at the machine shop made a mistake. Perhaps he was using a metric thread pitch gauge and it was close. Maybe he was not the head man in the shop and also didn't know that your saw was US made. Let us know if the nut from McMaster-Carr fits.
Thanks,
David

[Charles Lent]

The arbor nut for your saw is in stock at www.ereplacementparts.com
Arbor Nut
Part Number: A24970S

In Stock, 1 Available

$12.84


Since only 1 is available, you need to jump on this. It's item #228 in the parts list. I believe that the correct thread is an Acme thread. Ereplacementparts.com has always been my "go to" place for parts for my tools. I have never had a problem with them.

Charley

[orren countin]

The arbor nut for your saw is in stock at www.ereplacementparts.com
Arbor Nut
Part Number: A24970S

In Stock, 1 Available

$12.84


Since only 1 is available, you need to jump on this. It's item #228 in the parts list. I believe that the correct thread is an Acme thread. Ereplacementparts.com has always been my "go to" place for parts for my tools. I have never had a problem with them.

Charley

my bad. I should have clarified that the nut is on the bearing side or opposite side of blade. #37 on the parts list.

[orren countin]

Its very confusing. Saw says built in USA with foriegn parts. I measured the arbor shaft again as carefully as I could. I set the jaws to 1mm and they were visibly larger then the arbor threads. I set the jaws to .9mm and they seems to center up well on each thread. I set the caliper jaws to 3.6mm and again centered up well on the threads suggesting again a .9mm pitch. I counted threads in 1/4 inch and came up with 28 TPI same as .9mm pitch. The diameter of the shaft at the threads is .625. Ive ordered a set of repair files that allow for several different threads sizes but not .9. So that will be another clue. I must have got something fundamentally wrong here

[John K Jordan]

Its very confusing. Saw says built in USA with foriegn parts. I measured the arbor shaft again as carefully as I could. I set the jaws to 1mm and they were visibly larger then the arbor threads. I set the jaws to .9mm and they seems to center up well on each thread. I set the caliper jaws to 3.6mm and again centered up well on the threads suggesting again a .9mm pitch. I counted threads in 1/4 inch and came up with 28 TPI same as .9mm pitch. The diameter of the shaft at the threads is .625. Ive ordered a set of repair files that allow for several different threads sizes but not .9. So that will be another clue. I must have got something fundamentally wrong here

I never measure just one thread. For non metric threads to get TPI I set the calipers to one inch and count the number of threads in that span. At 1" the points of the calipers should fit nicely in the valleys of the threads. If it is 28 TPI you should count 28 peaks within that inch. If a full 1" of thread is not available measure as many threads as you can and do the math. This method assumes the threads are not too messed up for the calipers to seat nicely over a long enough span.

TPI.jpg

If it is really 28 TPI you should be able to hold a common UNF 1/4-28 bolt against the threads and have it fit perfectly. If not, it's something else. This also assumes the threads are no so messed up they can't be measured. If you have some good threads but they are not all the way to the end of the bolt you can cut off a section of the 1/4-28 bolt that will fit the good threads and use it as a gauge.

JKJ

[David Buchhauser]

I damaged threads on the arbor and nut for a Delta Unisaw 36-L552. I purchased the arbor but Delta doesnt know when the jamnut will be available. Could be months.
Its a right hand thread, 5/8 with .9 pitch or 28 TPI. I heard called extra fine thread. Ive been to hardware specialty stores and even 2 mechanical fab places declined. I think because of the finethread combined with 5/8.

Delta shows a A289885 part number. Maybe you know of another maker that uses the same jamnut?.

Any thoughts on how to get one?

Is your saw the Delta-L552-Type-1? If so the parts diagram shows that part #37 "Special Nut" fits the end of the arbor shaft. This is available here:
https://www.repairtoolparts.com/delt...7s-special-nut. Price is $8.59. Lead time is 1-2 weeks.
David

https://www.repairtoolparts.com/delt...e-1-parts-list

Delta 36-L552 Type 1 Parts Schematic.jpg Delta 36-L552 Type Special Nut.jpg

[John K Jordan]

...Lead time is 1-2 weeks.
...

This place claims delivery time is 1.8 days which sounds very odd: https://www.fix.com/parts/table-saw/...902012009847s/

But a quick search shows conflicting information for that part (Delta 902012009847S SPECIAL NUT) - one vendor indicates it's a left hand thread.

[David Buchhauser]

It says "Average delivery time via standard shipping: 1.8 days." I suppose he'll have to order one and find out.
David

special nut.jpg

[orren countin]

This place claims delivery time is 1.8 days which sounds very odd: https://www.fix.com/parts/table-saw/...902012009847s/

But a quick search shows conflicting information for that part (Delta 902012009847S SPECIAL NUT) - one vendor indicates it's a left hand thread.

Thanks for the input. After much running around, the arbor nut is a right hand thread and should be 28 TPI with a 5/8 opening. I found one on Ebay from seller "machacc" who appears to sell a bunch of unisaw parts and seems very knowledgable and said the nut he sold me would fit. I bought something from him before and only to 3 days to arrive.

[Rick Potter]

Correct me if I am mistaken, but as I understand it, a right tilt saw takes a left hand thread, while a left tilt saw takes a right hand thread.

This is to keep the nut from loosening from start/stop torque. The saw motor location is usually also different, left/right side.

[orren countin]

Correct me if I am mistaken, but as I understand it, a right tilt saw takes a left hand thread, while a left tilt saw takes a right hand thread.

This is to keep the nut from loosening from start/stop torque. The saw motor location is usually also different, left/right side.

sounds right. My saw is left tilt and the arbor nut for both the saw blade and the bearing on the opposite side are both right hand thread. The bearing side nut is a 5/8-28 thread. Not a common thread for such a large opening as Ive discovered.

[Bill Dufour]

Some car wheel lug nuts are 5/8 or a similar metric diameter. They may be a source. AFAIK Dodge no longer uses left hand lug nuts as of 1975 or so. I used a left handed one on my bench grinder.
Bill D