4x6 Bansaw Vise Slipping/Acme nut Repair or Replacement

[Kennyd]

Guys, my vise is slipping badly on my HDC 5x6 swiveling bandsaw (its a cheaper copy on the Grizzly G9742). Probably the same parts as the HF saw as well. The "nut" is only threaded 1/3 the way round and it pops loose easily. Searching "acme nut repair" turned up a few things on Google, my I saw lots of pictures of ones the have a brass button and spring to put pressure on the screw to I assume keep the threads engaged? Anybody ever modify this or have a link to a good repair? Grizzly does not have the part for sales online so I will have to call on Tuesday.

Thanks

 

[mhooper]

I had the same problem with a ENCO 7x12.
When I took it apart, I did not find any significant wear on either the nut or screw on the vise that would cause the slipping.
On my saw the hole in the nut is elliptical (one side threaded the other not).
When you crank the hand wheel clockwise, the nut flips over with the threaded part of the nut resting on the top of the screw closing the vise and when you crank the hand wheel ccw, the nut flips back with the smooth side resting on the screw releasing the vise. I assuming yours is probably the same.
I notice that the nut lifts up and off the screw when I tighten the hand wheel. The only thing holds it down is gravity.
I made a quick mod to the nut that seemed to stop the slipping.
I drilled a blind hole on the threaded side of the nut and installed a roll pin. I then trimmed down the roll pin until it just clears the yoke ( the U shaped piece around the nut)of the vise.
This prevents the nut from lifting up off the screw.
Hope this helps.
If you need a photo of the mod, let me know.
mhooper

 

[Kennyd]

Mhooper, that sounds like my setup exactly. I understand the mod you did, but a picture is always welcomed if its not to much trouble.

 

[mhooper]

Hello again
I have attached some photos mods to my bandsaw vise nut.
Photo bandsaw1 is of the screw, yoke and nut. The nut has a roll pin added to it.
Photo bandsaw2 is a close up of the nut.
Photo bandsaw3 is of the backside of the assembly indicating the the existing pin does not prevent the nut from lifting up. ( I had tried driving the existing pin down closer to the nut, but it prevented the nut from rotating and eventually worked it's way up. You can see were I ground on the nut trying to get the nut to rotate the the existing pin driven further down, no luck.)
Photo bandsaw4 is of the front side of the assembly and the new roll pin against the yolk. The new pin is pressed in a blind hole.
I think the original design would have worked if the tolerances on the exterior shape of the nut were better and if the original pin was not so easily moved.

If you want more pictures or better explanation, contact me.
mhooper

 

[Kennyd]

MH, that's great! :thumbzup:

Mine does NOT have that spring (flat metal) or the button it holds pressure on. I was thinking of adding that, do you know it's purpose and where its located in relation to the threads?

 

[mhooper]

I have no idea. It is really in the wrong position (90 deg off) to do any good.
The spring is also rather weak.

I would be interested to know if anyone else out there has this setup (or a different one).
mhooper

 

[Kennyd]

I spoke with Grizzly today, they have a new "updated" part, I hope it fits! It looks like it's one piece now.

Dear Kenny,

Thank you for your reply.

As mentioned before we do not have just the acme nut ( ref # 306) available anymore. However, we do have the hut and bracket for the vise in stock ( ref # 305V2). I have provided the part number and cost below:

Quantity	Item Number	Description	Price (each)
1	P9742305A	Bracket and nut	$21.75

 

[Kennyd]

Argh...the new "updated" part came this week. Its totally different, the Acme threads are smaller, the bolt hole is smaller, the part that slides in the vice is wider...Its also not a quick adjust style anymore-but that does not bother me.

Not sure what I am going to do, new part shown on the left:

 

[nnam]

I know this is several years later, but I think many people can still find this useful and encounter the same problem.
I just did. I have almost identical setup to "mhopper" above. However, one the two "wings" of the nuts can touch the "U" holder when rotate up, so it does what "mhopper" did with the roll pin. When rotate that wing up, it would force the nut down "somewhat".

For the "unanswered" question about the purpose of the spring loaded pin, I believe it is for "friction" purposes. Meaning without it, rotating the screw shaft may not turn the nut.

Over time, that pin is ground out, or dirt/grease prevents it from functioning well. The design of the pin is also questionable. It can be grounded out quickly given the sharp edges of the threads, and the pulling in out motion. I also wonder if the pin is hard steel.

So the solution I came up with yesterday that worked very well, is that replacing the pin with a steel ball (like bearing ball) 8 mm diameter. I think the exact diameter of that pin is 0.35" if you can find a ball that size.

The ball is hard, so will last a long time, easily sliding through the threads. It provides good pressure to keep enough fiction to rotate the nut along with the shaft.

The reason it's 90 degree between the two wings, because the designer didn't want it interfere with the force (gravity) pulling down the nut. If it's in another position, it can make things easier to slip, but not engage, or reverse, easy to engage, but can't slide back and forth.

If the friction is not enough, I would glue a little thin dish to the spring to push down the ball a bit more.

Also, make sure to clean them up good.

 

[nnam]

[update] after so many years, my mod still works great. Although I only use the saw once awhile.