Miter Slot issues - looking for guidance

Jim Mattheiss

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467
Location
Long Hill Township, NJ
Hello All:

I was reading the ongoing thread on cross cut sleds and was going to pile on there but decided to create a new thread.

I have a Jet contractor saw with a problem. The miter slot is not a consistent width - it narrows at the back.

I cannot make the runners wide enough for the front of the slot as it binds at the back. The binding occurs beyond the blade so I'm thinking that it could widen it without causing dramatic issues.

I'm thinking that a machine shop would charge more than the saw is really worth to do a precision job.

Any thoughts from the family?

Cheers

Jim
 
Sorry, I assume it's a cast iron top Jim? or aluminum?

Are both slots on the table this way? It would help to know how much difference there is between the front and back of the slot. You may need to build a jig with a dial gauge attached to determine how much material needs to be removed. And if the whole slot is tapered or if it's just a burr towards the end causing the issue.
 
Use a file and cut it out by hand. I bought a shaper with a similar issue. Didn't take long, and there probably isn't much material that needs to be removed.
 
Darren:

It's a cast iron top. I'm 99% sure that the issue effects both slots.

I will have to rig up a doo-hickey to measure the slots.

Some sort of sled that will ride on the table top and up against the left side of the slot. The dial indicator can be tilted to measure the distance to the far side of the slot. A little trigonometry and voila, we can determine the difference in the slot widths.

I don't have a straight edge accurate enough to measure the "straightness" of the side of the slot.

Jim
 
Sounds like you've got the right idea. Karl's right, a little filing should take care of the issue, and the dial gauge will save you a lot of time finding the right spots to file and how much needs to be done.

Can always start just filing, but it's hard to put it back if you take too much off. ;)
 
I'm with Karl. Cast iron is pretty soft when it meets a file. The concern would be determining with side of the slot was the "most" correct and trying to make the other one match it more closely. In other words, the side of the slot that you aligned your blade to would become the "master". This must have been a major pain when you were trying to align your saw(?).
 
Gosh, I thought ridgid was the only one that did that. Drives me crazy every time I try and do something. Still haven't figured out how to open up the granite.

Probably should add, I have the guide sized to fit the narrow end. I just make sure I hold toward the blade.
 
Another approach than a file would be to make a hardwood runner just a bit undersized so you could wrap some 220 thru 400 wet or dry sandpaper around it, and abrade the tighter end of the slot. Cast iron will abrade pretty easily.

Do you have a friend with a dial caliper to see just how much it tapers?
 
Gosh, I thought ridgid was the only one that did that. Drives me crazy every time I try and do something. Still haven't figured out how to open up the granite.

Probably should add, I have the guide sized to fit the narrow end. I just make sure I hold toward the blade.

Did you call Ridgid on the problem?

Probably could do the same with a diamond grit hone or something, but again, use a dial gauge to see where it needs to be honed at and how much needs to come off.
 
If it is just the ends at the last inch or maybe two, I wouldn't hesitate to take a file and go to work, slowly but I wouldn't give it a second thought.

Make a runner the fits on the other end and slide it back to where it sticks. Work on that area and just keep moving back. If it is just the last little bit and you opened it up to much you could compensate with longer runners. But if you go slow I doubt you going to create a problem.
 
Did you call Ridgid on the problem?

Probably could do the same with a diamond grit hone or something, but again, use a dial gauge to see where it needs to be honed at and how much needs to come off.

Yep, they want me to take it to the service center. 1 1/2 hour away. Wait on parts if they say it is bad. Will just buy a new saw one day and be done with it. All the problems I have had with this model, I should have done it to begin with.
 
Yep, they want me to take it to the service center. 1 1/2 hour away. Wait on parts if they say it is bad. Will just buy a new saw one day and be done with it. All the problems I have had with this model, I should have done it to begin with.

Yeah, other than my oscillating sander, haven't had much luck with that brand. The drill I had made by them had brush and trigger issues from the git go, I thought I might use it for small stuff around the shop new, but went to plug in the charger this week and it went flash with a pop inside...I'm done with it.
 
The thing to be careful of as you file is to try to make sure the two slots either remain or become accurately straight and parallel.

I might choose one edge of one of the slots as the reference, and start by making it as straight as possible. Then make the other edge of that slot parallel by sliding something, and filing away from only the non-reference edge until it slides evenly all along.

As you straighten the first edge of the second slot, you want to make sure it's parallel to the first slot, so that your blade will be properly aligned regardless of which slot you are using. Something like a double-runner sled with the file mounted as one of the runners might allow you to guide your file with the reference slot while fixing the other. This is probably needed only if the slots are far from parallel. However, a jig of some sort that can slide in both slots would be useful to check for parallel, no matter how you are removing metal.
 
Thanks to everyone for all the replies.

I became aware of the problem when I attempted to build the 2 runner cross-cut sled. Made the runners narrow and wedged them to the outside of the slots and glued them into place.

The sled slid beautifully in the middle of the table but bound towards the extreme front and back of the saw.

The saw is a Jet "Blue" model picked up on CL 2 years ago, so Jet is not gonna stand by it. It's 10 or 11 years old.

I'm going to do some checking and measuring and see what I come up with.

Thanks

Jim
 
a saw that old would be less likly to be bad,, i agree with turning the sled around and seeing what happens i bet its the sled not the slots...does a miter guage do the same thing in each slot? if not then try readjusting your sled to move threw easily then realign the fence on your sled..
 
Have you tried running ONE precision-sized piece down each slot?

If a piece of stock - preferably something like aluminum bar stock - goes the full length of each slot without binding, then the problem will be in your sled, not the saw.

Does your miter guage bind up in either slot? That'd be a clue.

If you set your rip fence to be exactly parallel to the edge of the miter slot, does a ripped piece of stock either bind at the back, or run loose at the back? If not, then the slot edge is parralel to the blade, so set the fence to the other edge of the slot and try again. If no problem there either, then the slot is okay, and it's back to checking the runners on your sled.

Are the sled runners wood, plastic, or metal? If wood, then humidity changes could be the problem, although it'll only take a couple thou of misalignment to cause your problem even with metal or HDPE runners.
 
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