R4512 ZC insert advice?

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Forum topic by IppoJ posted 03-10-2011 07:07 PM 11222 views 3 times favorited 15 replies Add to Favorites Watch
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28 posts in 2627 days

03-10-2011 07:07 PM

The throat of the Ridgid R4512 is apparently designed to use only the included steel insert, as such the ears that hold the leveling screws are designed for material ~3/32”.

I was hoping to get some expert experience to weigh in, will laminated MDF hold up to the task? I have some 1/2” mdf that I was going to laminate then route reliefs for the five leveling ears.

Or, is there a better alternative?
I’ll take a photo tonight, that may help.

15 replies so far

View crank49's profile


4030 posts in 2938 days

#1 posted 03-10-2011 09:55 PM

I have the Craftsman 21833, which is essentially the same identical saw with a different paint job. (I’m afraid that MDF made thin enough to sit on the ledge and leveling screws would be way too thin to support the work load.) I made my own insert using 10 ga aluminum plate. I traced the steel plate onto the aluminum with a scribe and cut it out with a jigsaw. It fits, and is strong enough to replace the steel plate. Starting with the blade in the lowest position I placed the blank insert in the table recess. Then clamped a 2×12 board to the table top, on top of the blank aluminum plate to hold it down as I cranked the saw blade up to its higest position; thus cutting a zero clearance slot. I used the crappy blade that came with the saw for this operation so I wouldn’t risk messing up my good blades. After I was done I ran a thin abrasive cutoff type blade along the slot with an angle grinder to give just a little relief. I then drilled 4 holes around the edges into which I epoxied 4 thin, rare earth magnets to hold the insert in place. The magnets need to be about .100” thick so they don’t protrude above the plate surface. I’m not suggesting anyone else try this method, it’s just how I solved my problem.

View IppoJ's profile


28 posts in 2627 days

#2 posted 03-10-2011 10:09 PM

crank, I honestly thought about doing the same thing but was worried about the coating on my blades, even after opening the slot up a bit.

I also thought about making a dado sized insert from alum or steel and fitting a wood insert into the opening.

Can I ask where you bought the aluminum stock?

View FaTToaD's profile


394 posts in 3108 days

#3 posted 03-10-2011 11:24 PM

I’m not sure if the 4512 insert is close to the 3650, but what I did was take some 1/2” MDF and use a straight bit in my router to clear out a section where the ears are. I just took a little off on each pass until it would sit flush. Like this:

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You can see more pictures here:

-- David

View crank49's profile


4030 posts in 2938 days

#4 posted 03-11-2011 02:15 AM

David, the 4512 is nothing like the 3650, cept maybe the color scheme. The insert sits on a tiny ledge that’s about 1/8” wide and about 1/8” below the table top. The bosses for the leveling screws stick out about 1/2” in 4 places. If you had to machine out the MDF like you show in your pictures, you would have to keep cutting till the edges were less than 1/8” thick.

IppoJ, I used to work for a contractor who also has a fabrication shop and steel yard. I bought it from them. You can usually buy aluminum from a steel yard. A good mail order supplier is McMaster Carr.

I forgot to mention that when you drop the blade all the way down its not quite low enough to put the blank insert in the slot without contacting the blade. I had to install a 7 1/4” blade I had laying around to start the slit. Then I switched to the 10” blade to finish.

I think the “insert in the insert” idea would work just fine.

One other point I would like to make. I think this saw would benefit from blade stabilizers so I bought some. Now if I install the stabilizers (thick, oversize washers) that better support the blade, none of my jigs, sleds, or inserts will fit because the blade position moves about 1/4”. :-(

View IppoJ's profile


28 posts in 2627 days

#5 posted 03-11-2011 05:59 PM

crank is correct, the distance from the table top to the ears is less than 1/8”.

I have a sheet of phenolic/linen that would be perfect and is the correct thickness but the piece I have isn’t long enough.
I think what I’m going to try is 1/8” masonite on top of 1/2” mdf for strength.

View David Grimes's profile

David Grimes

2078 posts in 2607 days

#6 posted 05-30-2011 07:37 AM

These are now available for the r4512:

I don’t think I’ll be fabricating these.

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

View rogerdodger's profile


15 posts in 2656 days

#7 posted 05-30-2011 12:31 PM

I made mine out of a plastic.
I ordered a strip of 3/8”x4”x48” and made three inserts.
Routered out for the leveling screws and made a clip to hold down the front.

View rogerdodger's profile


15 posts in 2656 days

#8 posted 05-30-2011 01:16 PM

I forgot to say I routered out a slot for the arbor as the 3/8”is a little to thick.
You can see the slot I’m talking about if you go to the link David Grimes posted.

I had made some inserts out of 1/4” plywood but the plywood shattered when trying to cut thin strips of red oak.The insert between the blade and fence flexed to much, not enough support because
the insert was to thin.

I had ordered 2 sheets of the plastic. The cost was about $48.00 with shipping.
You can work the plastic with woodworking tools.
So I ended up with 4 inserts for the R4512 and 2 inserts for my Ridgid miter saw.
And a 3/8”x3/4”x48” strip that I can use for jigs for the miter slot.

I still have to extend the slot on the zero clearance insert for the riving knife.
I think I can use my jigsaw for that.

View papadan's profile


3584 posts in 3336 days

#9 posted 05-30-2011 01:26 PM

Sounds like the 4512 uses thin inserts like my TS2400. Here is a tutorial I made about ZCIs for it made from 5/16 laminate flooring.

View Chipy's profile


374 posts in 2560 days

#10 posted 06-01-2011 10:25 PM

Leecraft inserts He has them all.

View DaddyZ's profile


2475 posts in 3008 days

#11 posted 06-01-2011 10:32 PM

Check out my Insert !!! More Pict’s under my projects

-- Pat - Worker of Wood, Collector of Tools, Father of one

View Kristopher's profile


78 posts in 2281 days

#12 posted 05-22-2012 06:37 PM

I bought the zero clearance dado insert from and it wouldn’t even go down on my R4510 at all. Had to return it. I think the seperator knife was in the way. And since I recently purchased the R4510 I don’t think I want to begin removing parts just to get a new part to fit that didn’t come with the tool. Guess, I’ll be making one from wood as I did with my old craftsman. It worked fine when I used it.

-- Kristopher, Westminster, SC - May you always believe in the magic!

View nwbusa's profile


1021 posts in 2253 days

#13 posted 05-22-2012 08:34 PM

I’ve made several ZCI throat plates for my R4512 using 1/8” hardboard. They fit perfectly and provide more than adequate support. A 1/4 sheet from the borg costs only a few bucks and there’s enough material to make seven or eight inserts.

-- John, BC, Canada

View IppoJ's profile


28 posts in 2627 days

#14 posted 05-25-2012 01:45 PM

popeye, I think the R4510 throat is a lot different than the R4512.
If you ordered the R4512 plate and it doesn’t fit I may be interested in buying it from you.

View daviddoria's profile


67 posts in 1906 days

#15 posted 02-12-2015 12:14 AM


You just set the 1/8” hardboard on top of the ears with the leveling screws in the throat? It seems like that would be a little dicey, anyone have any ideas on how to secure something this thin?

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