Warning to Minimax CU300 owners, and possibly other sliders with scoring blades

[mark mcfarlane]

I use my scoring blade all the time. I get better cuts on the underside of hardwood using it, so it is (was) pretty much always sticking above the table.

The problem: A few months ago I had to do a 45 degree cut, so I tilted the blade 45 degrees (the scoring also tilts), turned on the saw, and voila, the scorer belt shredded.

The root cause: The end of the shaft the holds the scorer blade was tight against the bottom of the aluminum blade insert, preventing it from turning. FYI: When you tilt the main blade, the scorer raises slightly higher above the blade insert.

The immediate solution: $80 for a new belt shipped from Parts Pronto. Ouch.

The caution: Lower the scoring blade before doing a tilt. If the scoring blade is needed, make sure it doesn't bind before turning on the saw.

There is now a sign on my saw next to the til wheel to remind me of this :).

I hope this saves someone else $80.

FYI - changing this belt was pretty simple. It took less than an hour, and if there is a next time it will probably take 10 minutes.

Cheers,
SaveSave
SaveSave

[Jim Becker]

Hmm...I don't recall having this issue, but then again, I also don't recall if I had the scoring blade in play for any bevel cuts. I don't do them very often.

[mark mcfarlane]

It's easy to confirm if this will be a problem on any saw: Raise the scoring blade all the way, then tilt the blade while periodically checking if the scorer rubs as you approach 45 degrees, by manually turning the scoring blade. If it spins freely at 45 degrees you should be safe. In my CU300 it starts binding around 43 degrees...

If I loosen the insert plate, on my saw the scoring blade shaft actually lifts the insert plate off the table as I tilt.

[John TenEyck]

This sounds like a design oversight, or is the scoring function specifically designed to be used only for 90° cuts? With your saw, could you cut down the scoring blade shaft to give you the additional 2° needed?

John

[David Kumm]

Was the old belt labeled? There should be a lot cheaper alternative than Parts Pronto for belts. Dave

[mark mcfarlane]

This sounds like a design oversight, or is the scoring function specifically designed to be used only for 90° cuts? With your saw, could you cut down the scoring blade shaft to give you the additional 2° needed?

John

I'm pretty sure it was the nut on the scorer shaft that was hitting. Maybe a smaller profile nut.

i also feel like this was a design defect.

[mark mcfarlane]

Was the old belt labeled? There should be a lot cheaper alternative than Parts Pronto for belts. Dave

The old belt was clearly labeled with manufacturer and part number. An hour or two on Google didn't pay off. I could have spent more time looking, but was impatient to get a new belt, then had it sit on the bench for 2 months.

[Scott Buehler]

I can tilt my scoring blade and cut just fine on my SCM, never had any problems, I wonder if something was misaligned?

[Jim Becker]

You might want to ask Sam Blasco about this...

[Steve Jenkins]

You said raise the scoring blade all the way up. I can’t imagine why you would need to do that.

[mark mcfarlane]

You might want to ask Sam Blasco about this...

I spoke with Sam about it the day it happened. He said to just file the insert plate or turn the saw on and run up the scoring blade. He wasn't too concerned. Neither of his fixes would have helped though, since the problem was not the blade binding against the insert (which I assumed was the problem), it was the arbor hitting the insert.

Sam also made an alternate suggestion to source the belt from an auto parts store. I should have tried that, but I called Parts Pronto and they said the belt was $50 so I said go ahead and ship it. Then they charged about $30 for shipping the belt.

[Bill Orbine]

I had a much older SCMI slider that had that issue with the scoring shaft hitting the throat plate. I do recall the manual was specific about lowering and not using the scoring cutter.

[mark mcfarlane]

You said raise the scoring blade all the way up. I can’t imagine why you would need to do that.

Hi Steve,

Some scoring blades (like mine) are trapezoidal in cross section, so increasing the scoring blade height gives you a wider kerf. You raise the scorer just enough to match the kerf of the main blade. A fixed-width scoring blade that exactly matches your main blade is probably better, but the trapezoidal one came for free with the CU300 and I haven't replaced it.

For my CU300 setup with the stock scorer and a WWII as the main blade, I get the cleanest crosscut in plywood when I raise the scorer all the way up (3mm protrusion @ max), then back it off 3/4 of a turn, leaving the scorer protrusion at 1.6mm. So 'all the way up' isn't a very big number on this machine This optimal scorer height was determined through experimentation.

[mark mcfarlane]

I had a much older SCMI slider that had that issue with the scoring shaft hitting the throat plate. I do recall the manual was specific about lowering and not using the scoring cutter.

Oh, there is a manual :rolleyes:...

[mark mcfarlane]

I can tilt my scoring blade and cut just fine on my SCM, never had any problems, I wonder if something was misaligned?

Misalignment is possible. Are you on a late model CU300? I suspect each machine is different. Mine is a 2017 CU300.

[Jim Becker]

I didn't realize that the OEM scoring blade is trapezoidal...I've never used it as I somehow also ended up with a fixed width scoring blade that's .125" and matches my Forrest blades exactly. I only raise the scoring blade just enough to...um, score...the material. :)

[David Kumm]

A conical scorer is a good choice if there are stops on the adjustment lever so the blade can be lowered and then returned to the correct height easily. If the height is adjusted with a wrench in the cast iron top and has no stop, the split scorer is the best choice. I mark the lateral adjustment so I don't use it in error but then the scorer can be any height and work. If the ply isn't tight to the table, the scorer needs more height and still might go fuzzy. I use Mac's clamps and that means the scorer doesn't need to protrude much. Dave

[mark mcfarlane]

I didn't realize that the OEM scoring blade is trapezoidal...I've never used it as I somehow also ended up with a fixed width scoring blade that's .125" and matches my Forrest blades exactly. I only raise the scoring blade just enough to...um, score...the material. :)

i measured my scoring blade with calipers. It is trapezoidal. Like David said, the best height is also a function of the flatness of the stock.