How flat should a ZCTP be?

[jstevens]

One of my dumber questions: how flat should a ZCTP be? I just bought an aftermarket ZCTP for my BT3100, and it has a slight crown, maybe 3/64". Is that going to be a problem?

Regards,

John

[LCHIEN]

seems like a lot to me. Mostly a problem for cutting dadoes tenons and non-thru cut stuff.
Its not to hard to make your own. some guys have taken flooring scraps which are pretty flat and made ZCTPs from them.
MDF is also very flat

[Cochese]

See if you can use some equal and opposite deflection to get it more in spec.

[JSUPreston]

Is it crowning because of it being too snug? If so, I would think a couple of passes over some sand paper might shave it down enough to let it fit better.

[cabinetman]

I would want it flat.

.

[jstevens]

Hi guys, thanks for all your suggestions. It's made of a plastic-like material, slippery like UHMW, so I doubt it can be sanded or otherwise shaped. Now that I've measured it against a straight edge, I can tell it's crowned a good 1/16"

Yeah, I think I want it flatter than that.

Regards,

John

[Knottscott]

A throat insert is a pretty significant component in the system. If it's not flat, or if it flexes, it'll effect the cuts (but the blade usually takes the blame! ).

[RodKirby]

A throat insert is a pretty significant component in the system. If it's not flat, or if it flexes, it'll effect the cuts (but the blade usually takes the blame! ).

ditto - ditto, and...

If you attempt to force the work down, to flatten it, as you're feeding the work - could be dangerous!

[Stytooner]

This is one of my plates. I just checked the rest of the batch I have here and they are the same way.
These should be flat or have the crown down.
It is a QC issue on my part and a failure to follow instructions on my Son's part.
Sometimes the plastic material does have a slight bend one way or another for various different reasons. Heat, storage and shipping can have an effect.

These are now all totally made on my cnc router. I cut the blanks out on the BT first, but after that it's all machined on the router in steps.
The first step before mounting these on the router jig is to crown them. All crowns are SUPPOSED to go down on the plate, but up in the jig. The jig holds them flat. This lets the plates level out when installed. Normally there is no crown to speak of, so this is why he probably overlooked it. He isn't quite as aware of why these need to be done this way as I am, but
he soon will be.

We will be milling a new batch soon and I will include another plate along with the rest of your other order, John.
In the meantime though, if you have a hair dryer, you may be able to get this one working correctly by reversing that crown.

Support both ends of the plate leaving space under the middle. Heat up the whole plate with emphasis on the center. Add some weight to the middle once warmed up and let sit to cool.
This should give a crown the other way and allow it to sit flat once the ends are screwed down.
My apologies on this.

[jstevens]

Hi, Lee. I didn't identify the manufacturer on purpose--I know you're a good guy and I always trusted that you would take care of any defect if there was one.

I would have brought this to your attention w/o posting here except I didn't want to waste your time if there was not truly a problem, and I thought that I could inquire here without affecting your name or your business. You're not only a good businessman but a gentleman as well. There really is no need for any apology--anyone can make a mistake, so IMO it's not the existence of a mistake that matters, but how the mistakes are corrected. Thank you very much for taking care of this "hiccup." I'll try your suggested fix and get back to you--if it works, then no need to send a replacement.

For those who have been reading this thread, here are some important things to know if before making any judgment on Lee's product. Aside from the crown, the ZCTP is a beautiful piece of work, very precisely machined and nicely finished. Ordering was easy, and I received a discount using the code that was on the home page of Lee's new web site. I received the product within days after I ordered, so Lee probably shipped right away.

I didn't mention these things in my original post because my only purpose was to figure out whether it was normal to have some upward bowing in an aftermarket ZCTP. Now that the manufacturer's identity has been revealed, it's only fair that I mention the positives as well as the one and only negative.

Regards,

John

[jdon]

The two preceding posts epitomize what a great and exceptional forum this is!