# need a fix for Grizzly "half nut" on bandsaw vise screw



## josef (Feb 12, 2019)

I have a Grizzly G1758 horizontal bandsaw that I bought new many years ago.  From time to time I've fought with the half nut which seems to work only half the time.  I replaced it once thinking that it was worn out.  I've cleaned it, lubed it, cursed it, and finally am ready to replace it with a real nut if I can find out what the acme thread size is.  Anybody know?
The other option which may be better is to just replace the screw  and use a regular acme nut.  Suggestions?


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## pdentrem (Feb 12, 2019)

We have the same problem. The drops and you cannot tighten the vice, without lifting the nut up by hand. Never looked into it.


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## josef (Feb 12, 2019)

Yep.  I've been lifting it by hand for a while and now it won't even reliably work that way.  So I've got to do something.


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## Glenn Brooks (Feb 27, 2019)

Josef,  I have the same problem on my Grizzly bandsaw. I went through a goatscrew ordering a replacement nut and acme thread for my saw. The new parts are larger ID than the old one, so didn’t fit. I returned them to drizzly and they lost them for a month in their store.  When I replaced the old lead screw and nut, it worked better after  I dissassembled and cleaned the threads.  Nothing else changed except I cleaned out all the old grease, scarf and chips.

If you find a better solution, please let me know. Grizzly’s half nut solution is a real bad idea, that they don’t seem interested in solving.

Glenn


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## NortonDommi (Feb 27, 2019)

I had the same problem.  Massaged the nut a bit so it would work as designed and from memory worked the seat for the spring.  That was about 6 years ago and it has worked perfectly since.  I trued the vice up at the same time.  Making sure the vice is evenly loaded is a must and I cheat by having an Irwin quick clamp on hand for the top of the jaws on large or awkward pieces.  I drilled a few holes plus made some T-nuts for the central slot to use the clamp set off the mill.  Faster and stronger than the vise in many cases especially odd shaped offcuts.


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## josef (Feb 27, 2019)

Well, I went the route of buying an acme nut and screw from McMaster Carr.  I bought a 1" screw which was bigger than needed.  I had to bore out the drizzly cast piece that the screw goes through and that the vise jaw screws to.  Turned down the end of the acme screw to be the same as the old screw.  It all works pretty well.  Sometimes there is a little binding which is fixed by jiggling the vise jaw.  I really should have ordered a left hand thread screw but at least I'm not fighting that half nut or grizzly either.  I've found that fighting with Grizzly is pretty much a lost cause.
I had already been through cleaning the old half nut and working on the spring and it still didn't work.


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## Glenn Brooks (Feb 28, 2019)

How did you secure the acme nut to the Grizzly nut casting?  Any photos??

Thanks
Glenn


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## josef (Mar 1, 2019)

Sorry, no photos.  But I did not secure the nut.  It floats right where the old half-nut floated and is stopped in its rotation by the same split pin that stopped the half-nut.  So I kind of lucked out because the size of the nut for the 1" acme screw was just right for that to work.


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## Swissmat (Jun 19, 2020)

Don't sell your bandsaws just yet ... I had the same problem with my 10x17 .. on mine there are two parts to the casting that goes around the ACME screw, the larger we'll consider the housing (214) and the smaller the offset-half-ACME nut (213) .. when my vise began to slip I considered worn out ACME threads on either the screw or the nut, but it turned out to be neither .. there is a roll-pin (215) going through the top of the housing which protrudes into the space where the nut lives, it engages with said nut when the vise handle is turned and pushes the half ACME thread onto the ACME screw .. if your vise doesn't clamp any longer, try tapping that pin down another 1/16 of an inch and try again .. as the pin wears on the casting, it'll have to be pushed further over the years .. one might be tempted to replace the wearing pin with a hardened piece of steel, but that woudl only result in the actual casting wearing down .. which is way more costly of a replacement than a simple roll pin .. hope this helps, fixed my vise issue for good ... cheers


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## pdentrem (Jun 20, 2020)

I will check that out on Monday.


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## jwmay (May 2, 2021)

Any further conclusions reached here?  I've been trying to get mine to work with no luck too. The quick release feature is much less important to me than the secure clamping.  I may have to buy an acme nut as well.


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## jwmay (May 10, 2021)

Just for anybody else that may wander to here:
My problem ended up being a worn leadscrew.  After cleaning the chips and gunk out of the nut, my clamping problem continued.  I found that i have no clamping problem if I put a 2" thick spacer between the work and the moveable jaw. So moving the clamping nut back by two inches puts me in pristine leadscrew territory.  I'm guessing if I use this thing another 30 years, I may have to put in a 4" spacer at that point.


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## Jason812 (Jun 15, 2021)

Swissmat said:


> Don't sell your bandsaws just yet ... I had the same problem with my 10x17 .. on mine there are two parts to the casting that goes around the ACME screw, the larger we'll consider the housing (214) and the smaller the offset-half-ACME nut (213) .. when my vise began to slip I considered worn out ACME threads on either the screw or the nut, but it turned out to be neither .. there is a roll-pin (215) going through the top of the housing which protrudes into the space where the nut lives, it engages with said nut when the vise handle is turned and pushes the half ACME thread onto the ACME screw .. if your vise doesn't clamp any longer, try tapping that pin down another 1/16 of an inch and try again .. as the pin wears on the casting, it'll have to be pushed further over the years .. one might be tempted to replace the wearing pin with a hardened piece of steel, but that woudl only result in the actual casting wearing down .. which is way more costly of a replacement than a simple roll pin .. hope this helps, fixed my vise issue for good ... cheers
> 
> View attachment 328216


This past weekend I picked up a barely, if at all, used G0651 and the vise wouldn't tighten.  The pin (215)  wasn't a roll pin but a solid pin with a poor attempt at knurling to keep in in place.  I could drive it down slightly and get the vise to tighten but then it would push back to the top and the vise would slip.  I simply made a slightly larger diameter pin and so far it is working just fine.  I should have thought about it a little more and just put a roll pin in there instead.

If that fails, I'll get a piece of left handed acme all thread and a solid nut and just lose the quick acting capability.


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## Tool Guy (Jun 26, 2021)

@Jason812  I just fixed mine 15 minutes ago.  What I noticed was that pin was installed upside down from the factory.  The gnurled end was at the bottom basically not having any effect of keeping it in.  I flipped it so gnurled side was on top, tapped it in with a punch and it works great now.  I'm sure it may wear and need to be sunk in more in the future, but looks promising.  If it continues to move I'll surely switch to a roll pin and try that.
I had called Grizzly and explained my problem.  They told me they had zero reports about problems with the vise.  Looking around, I can see why.  We fix it ourselves.  Thanks Drizzly.
Thanks to @Swissmat for the solution.  I didn't even notice that pin.


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