Unisaw arbor wear.

[Lenny Howard]

At work we have a 5-6 year old Delta Unisaw that we keep setup mostly for cutting dadoes. We replaced the arbor about two years ago because the threads developed wear in the area where the stack dado chippers would be, making it impossible to use a blade. Only the very outer end of the shaft would still hold the nut. Now the second one is worn out as well. We have only used quality blades, Forrest and Freud.
Our Powermatic saw is over 14 years old and handles the bulk of the work with no such issues.
Has anyone else heard of problems like this being reported by others Unisaw users ?

Our shop manager hasn't had much like, so far, finding replacement parts that are in stock. Any recommendations on who to contact?

Since the second one also wore out so fast I wondered if it would pay to have a machinist make one from a higher grade of steel. :confused: I don't think the boss will go for that option but I still think it should be considered. What do the rest of you think?

Thanks for any and all suggestions!
Lenny
http://www.heartwoodmillworks.com/

[Neil Brooks]

Might want to give these folks a call, and see what they might recommend:

LINK (http://www.sawcenter.com/)

[Bob Wingard]

There really should not be any wear unless the chippers are slipping ... and ... the chippers shouldn't be slipping if they are held tightly enough by the nut.

It sounds like either the nut isn't tight enough or someone is being WAY too aggressive with the feed rate.

[mickey cassiba]

If the saw is used as a dedicated dado machine, and it's making money at it, a custom arbor would be an option. I'm with Bob though. It does sound as though the chippers are slipping. An old machinist trick that may work here is to use paper between the chippers/blades along with a squirt of light oil or WD40. I've done this many times to help secure fixturing or workpieces on mill beds. the paper should not appreciably change the size of your dados as long as you don't try to use card stock or anything very thick. By the way, in all my years at Delta, the only time I saw wear on the arbor threads was when arbor hole adapters were used in attempt to run an oversize blade. the arbors are hardened after threading.

[glenn bradley]

The design parameters are obviously being exceeded. Wearing out a hardened arbor is no small feat. I would definitely consider having a custom arbor made but, don't know that even that will accept the workload being asked of the machine. If the shop is working that feature that hard, maybe stepping up to an industrial machine is in order. You have to consider though that times are tight and you can replace a lot of arbors for the cost of a continuous duty machine.

[Bob Wingard]

Wearing out a hardened arbor is no small feat.


I don't think most table saw arbors are hardened ... but, maybe they should be.

[Lenny Howard]

Thanks for all the replies! The saw gets a lot of use (and no doubt some abuse) with the three of us in the shop and then the occasional ones from the construction side of the company (who are even better than us at wearing out tools before their time!) :)

Mickey, We actually use magnetic shims that came with our Forrest Dado set.
I don't think it's a case of the nut not getting tightened ... in fact the first time it happened I suspected the opposite to be the case. The person who was responsible for that is no longer with us however.

I DO suspect feed rate could be an issue.

Thanks again!
Lenny

[Gary McKown]

Interesting! Over on another ('Net) forum there is a thread about tearing up an X5 Unisaw arbor and no replacement available from Delta or anywhere else.

[keith micinski]

How would feed rate cause the arbor to wear? It seems like that would hurt the bearings but thats about all. To me it seems like the only way the Arbor could be worn was if the arbor was rotating at a different speed then what ever is on it. I guess if your saying the feed rate was actually causing the arbor to slip inside of the chippers or blades that could be something but it sure seems like you would have to be going crazy with feed rate to do that and not bog the saw down.

[Ronald Blue]

You didn't say specifically but is the diameter of the arbor getting smaller as well. The result being whatever you mount on it has excessive slop. However if its just a matter of the threads "wearing" out it is a different issue. I don't know if it uses standard 60 degree threads or an acme thread which would be much much stronger in an application like this. If the diameter is smaller then there may be a slipping issue, but if the threads are simply wearing out that's a result of many on and off cycles. One should replace the nut periodically to help prolong thread life.

[Matt Meiser]

There's an arbor or two on EBay right now. That honestly might be your best bet for finding one right now. Delta is doing their best to destroy any image the brand had left by not having parts available. I recently heard that one of local places couldn't get someone an arbor nut for anything.

[Dave Lehnert]

Talking about Delta. I had a friend who needed a belt for an old Delta table saw. It had been on back order for a long time and a woodworking tool dealer said people come in often looking for that same belt. She needed the saw for a project so she called the manufacture named on the belt. Belt manufacture said "That is a special order belt, will take us a few days to make it" She had the new belt in about a week. Still on back order from Delta.

[Ed Edwards]

Mickey,
I certainly don't doubt what you say.

An old machinist trick that may work here is to use paper between the chippers/blades along with a squirt of light oil or WD40. I've done this many times to help secure fixturing or workpieces on mill beds. the paper should not appreciably change the size of your dados as long as you don't try to use card stock or anything very thick.

But could you please explain what happens and educate this old fart? But I'm always willing to learn.

Regards,
Ed

[Lenny Howard]

You didn't say specifically but is the diameter of the arbor getting smaller as well. The result being whatever you mount on it has excessive slop. However if its just a matter of the threads "wearing" out it is a different issue. I don't know if it uses standard 60 degree threads or an acme thread which would be much much stronger in an application like this. If the diameter is smaller then there may be a slipping issue, but if the threads are simply wearing out that's a result of many on and off cycles. One should replace the nut periodically to help prolong thread life.

Interesting that another forum has a similar thread going. I suspect there will be more!

The arbor is wearing down (threads have practically disappeared) in the area that dado blade takes up. (.55mm +/-difference in diameter) Still enough thread at the outer end of the arbor, so we are able to mount the dado for 3/4" width. The owner (my boss) has decided to look into having a new one made. I think he made the right call!

[Lenny Howard]

The design parameters are obviously being exceeded. Wearing out a hardened arbor is no small feat. I would definitely consider having a custom arbor made but, don't know that even that will accept the workload being asked of the machine. If the shop is working that feature that hard, maybe stepping up to an industrial machine is in order. You have to consider though that times are tight and you can replace a lot of arbors for the cost of a continuous duty machine.

Just to clarify, this Delta Unisaw is an "Industrial" machine!!! :eek:... at least it says so on the label on the front of the saw! :)
I think though, what you are saying is, we should look at another Powermatic 66 or something along that line .... I tend to agree. Which is easy to do since it's not MY money we are talking about. ;)

[Kent Chasson]

Interesting that another forum has a similar thread going. I suspect there will be more!

The arbor is wearing down (threads have practically disappeared) in the area that dado blade takes up. (.55mm +/-difference in diameter) Still enough thread at the outer end of the arbor, so we are able to mount the dado for 3/4" width. The owner (my boss) has decided to look into having a new one made. I think he made the right call!

I can't see any good reason why that should happen. Sounds like the blades are slipping and the arbor is spinning inside them. That should be noticeable right away when sawing. I would put some more work into figuring out why it's happening before machining a new arbor or buying a new saw. I can't believe it's the fault of the arbor

By the way, I bought an arbor from the "Saw Center" (link above) and it has been fine for several years.

[Jeff Duncan]

Just to clarify, this Delta Unisaw is an "Industrial" machine!!! :eek:... at least it says so on the label on the front of the saw! :)
I think though, what you are saying is, we should look at another Powermatic 66 or something along that line .... I tend to agree. Which is easy to do since it's not MY money we are talking about. ;)

Delta and industrial should rarely be used in the same sentence:eek: They did offer a handful of machines that were heavy.....the Punisaw just wasn't one of them;)

Now I'm thinking a used Tanny would do the trick:D Mainly b/c one was for sale locally recently for $400. Only problem is you would need to re-bore your blades for the bigger arbor.

good luck,
JeffD

[Greg Portland]

I can't see any good reason why that should happen. Sounds like the blades are slipping and the arbor is spinning inside them.+1. How many people work on that machine and do they know the right way to assemble & tighten a dado stack? If the chipper teeth were touching the outer blade teeth then you could end up with a loose blade condition. I can't see where "hardness" is an issue since the parts shouldn't be rubbing against each other.

[hank dekeyser]

Being that their is enough room for it, I would try a brass tube in an effort to protect the threads. If the arbor itself is literally being worn down, it would present itself as run out in the blade and vibration. If you are merely flattening the threads, the brass tube would likely work. Or have a "worn out" arbor you already have machined down to accept a hardened shaft bushing and have a different thread machined on the arbor ? Or heliarc the threaded portion where the (dadoe) blade will be, refresh the bolt threads and have it machined true and harden it? Years back I worked in a shop where we used an old "contractors 9 inch" as a dedicated dadoe machine for tennons and never had an issue with it. They still use it to this day (umm like 25 + years later) Spending the money on a new saw in my mind is silly. but then you didnt really say what you're running through it. my 2 cents