Molder/Dado Arbor

[judaspre1982]

I purchased a SS molder/ dado arbor(p/n 505506) last month and just got to use it with my Amana stacked dado set.I grooved six 2x4x24in pine boards.Grooves were 3/4in W x 3/4 in D. Depth was cut in two passes at 3/8 in each cut. I assembled the stacked dado on the SS arbor according to instructions.After cutting all my groves when I went to disassemble the arbor the tongued washer had spun into the arbor shaft and gouged the threads. The tongue on the washer was almost sheared off. Needless to say trying to get the washer off the shaft was more than a challenge. Tongue washer was assembled in the grove and between last washer and nut as per instructions. I tightend nut on shaft good and snug. I do not know when the damage happened either during grooving or when I tightned the nut on the shaft. The shaft threads and the tongue washer are history along with the $27.00 plus shipping I paid for the arbor. There are no torque specs listed on package for tightening nut on shaft so I used my best judgement. I have used other arbors that had tongue washers and never had this problem. Has anyone else ever had this happen? How tight should arbor nut be? Any ideas as to why this may have happened-----other than the back of the package says Made in Taiwan:D ------ would be appreciated--------judaspre1982

[bettyt44720]

i recently bought a used upgrade set of tables(500 to 510) that came with a shopsmith wobble dado that was mounted on a shopsmith arbor among other things. when i removed the arbor which was very tight(it took two of the large arbor wrenches) the tongue was missing on the washer but there was no damage to the arbor. that kinda puzzled me. figured it happened before i got it. was going to put it on my list for my next order from shopsmith if it is even available by itself.seems cost prohibitive to order it by itself. could not find it online or in any catalog that i have. maybe if someone has any paperwork from the molder/dado arbor it might have a part number.

[a1gutterman]

Hi Bob,
Sometimes you can order a part like that through customer service, even without a part number.:)

[judaspre1982]

I will call SS cust serv and see what they say about it. I wonder how crucial the tongue in the washer really is. I may be able to clean up the threads but they are pretty fine and dont know what die size they are. I could grind away what tongue is left and just use the washer but I dont know if it is a safty issue or not. The tongue and the groove in the arbor shaft were made for some reason . If the washer alone could be purchased that woud be good but I wonder if the same thing would happen. The big ? is why did it happen? Soft metal? Slop in the fit of the tongue and keyway?Over tightening? I would have to see another arbor set to inspect better. I suspect the washer was not hardened enough for the purpose it serves. As usual the weakest link in whole set up is likely to cost pennies to make but cost the customers big $$$ when when they fail. At least no one was hurt. judaspr1982

[Nick]

I'm sure that Shopsmith will replace your parts as they are so new, but to prevent this happening in the future you should know that problems like this typically arise from stacking the trimmers and the chippers improperly. There are two ways to get yourself in trouble.

1. The teeth of the chippers must nest in the gullets of the trimmers. Furthermore no teeth anywhere in your stack should contact another tooth or the body of another blade. It is absurdly easy to overlook this, particularly with the 6" and 8" Amana sets that I use. More than once I have found the tooth of a chipper overlapping the blade body of a trimmer after I had tightened the nut on the arbor. If you make a cut with dado like this, the stack will shift, parts will start to move, and damage may result.

2. You should build your stack from the end of the arbor in. Use your spacers so the nut is as close to the end of the arbor as possible, but still safely engaged with the threads. If you don't do this, the arbor, the nut, and the washer will rub on the tiebar -- and damage may result. This particular problem will also booger the threads and/or strip the tongue off the washer just as you describe.

...I wonder how crucial the tongue in the washer really is...
Pretty dag-gone. Unless you don't mind being chased all over your shop by whirling trimmers and chippers. The tongue in the washer and the groove in the arbor prevent the nut from turning off the arbor when in use.

With all good wishes,

[judaspre1982]

Thanks for the tips Nick. I did stack the set up as recommended in Amanas instruction manual but as you said things may have moved when I tightened it all down. I will know what to look for the next time I use the set up. How tight should you draw down on the arbor nut? Sounds like it needs to be pretty snug to keep thing in place and maybe check component alignment after a few operations. I will try to come up with a way to keep all cutters in place while tightening the arbor nut. Something that is adjustable and conforms to the chipper star pattern and cutter blades. It will wedge between the gullets to keep things aligned. Maybe use an old saw blade with holes drilled in multiple positions in the circumference to put pins in and line up to the stacked dado circumference. Now I have something to work on until my new arbor comes in;) . judaspre1982

[Nick]

I simply tighten the nut normally; no need to get out the torsion wrench or the breaker bar. I make it a point never to strong-arm anything -- too easy to damage something with too much pressure. If the dado assembly won't hold together with normal, every-day, run-of-the-mill tightening, then you have problems that overtightening will not fix.

As for the jig, it's my opinion that you're over-thinking the problem because you've had one bad experience. Careful stacking and a preflight check is all that should be needed. Once again, if you have to build a jig to maintain the orientation of the parts, then you probably have other problems that a jig won't fix.

With all good wishes,

[judaspre1982]

Point taken Nick. I will ixnay on the Rub Goldberg. Thank you for all your help.------- Dave---- judaspre1982