Old SMT needs makeover

[mdutch]

It was spring. The old saw was cleaned, top repainted, sanded and waxed. A brand new Fr80T blade bursting through a brand new T-Nuts ZCTP. It was like watching the daffodils come up!

Then came the SMT. It's been out of whack for months. And I know IIIIII didn't break it!! So, I ran out of things to do and the long frustrating alignment commenced tonight...

Caveat:
This is the FIRST time I've had to loosen the SMT base screws, (no, REALLY) and the front LEFT screw was loose. (Well, there's a clue! No wonder it wasn't square!)

But after adjustment, I tried to re-tighten that left front base screw and <tweak!> the front left screw is.... uh... not tight. And still turning... It's stripped!

Note: I had just finished adjusting one of the locking clamp screws and it too was partially stripped. But good enough that it was holding.

So, big questions. With two out of four holes in Part #15 "Guide Bar" stripped, how do I go about replacing it? Do you get a new part... from.... ??? Or, is the guide-bar made from standard aluminum extrusion that I can get a piece of and cut to length?

I had a passing thought of resorting to a drop of JB Weld in the hole...

[Stytooner]

Since the bars are aluminum, I'd say that you can just flip it around and redrill it for some short sheet metal screws. Should be easy enough to do.

[mdutch]

Since the bars are aluminum, I'd say that you can just flip it around and redrill it for some short sheet metal screws. Should be easy enough to do.

They're "U" channel alum. The self-tapping screws bite into the groove and only cut threads on about 30% of their surface. This is a design flaw IMHO, the exploded diagrams are drawn as if they intended solid bars with tapped holes. Why they have thread-cutting screws at an adjustment point beats the "S" out of me!

[Stytooner]

I know what you mean. Just fill the void with some hardwood and use some wood screws.

[mdutch]

Has anyone else experienced vertical "creep" when fully clamping the SMT Miter Locking Clamps (Item #30 Partno. 969915-002) down? I noticed that on two of mine there's an upward "drift" which is certainly messing with alignment.

Currently, my SMT is disassembled for inspection. Both of the Guide Bars (Item #15, Partno. 664137-001) are shot. The Holder Plates (Item #16, Partno. 969916-006) are deformed, and flex when the clamps are locked down.

I contacting Ryobi parts and ordered two new Guide Bars, plus four new Miter Locking Clamps (going to see how much wear there is) and will rebuild all four of my clamps. Tried to purchase four new Holder Plates but they are now "obsolete". Since they flex, I'm thinking of coming up with a re-design out of milled aluminum.

See I think the whole design is all wrong. There's a lot of upward stress on the screws when the clamps are engaged (which is why they added set-screws to put more lateral pressure on the threads and minimize stripping). It's no wonder they tend to strip out. And the Holder Plates are too thin -- which tend to deform them. The guide bars should be made of solid bar-stock, fully threaded, instead of the aluminum channel with just a small percent of the threads engaged. And the Holder Plates should be replaced with a bracket made of machined aluminum or steel. Otherwise, it's a guaranteed failure over time.

As an experiment, I took my old stripped-out guide-bars and flipped them 90deg, and drilled and tapped for slightly larger (12-24) machine screws. I'm going to see if these fully-cut threads work better while I look for some solid alum. stock to prototype some better ones, which I will run for the original 10-24 threads. Having fully cut threads should eliminate the need for the set-screw.

Thoughts? Is anyone still reading this? ('bout an "eleven" on the boring meter, I think!)