Tooling a Moulder for Kerfing Jamb Stock

      Can a saw blade or dado blade be adapted for use on a moulder to cut 1/8-inch kerfs? August 18, 2009

I'm trying to run a kerfed door jamb. Does anyone know where I can get a saw blade style knife that would fit on the vertical spindles on my molding machine?

Forum Responses
(Solid Wood Machining Forum)
From contributor A:
I had my sharpening company bore out (2) 6" Amana dado sets so they would fit on my shaper arbor. A 6" set is about $130. They have proved to be very useful for cutting tenons to do applications like yours.

From contributor J:
We run our drywall return kerfs with a straight rebate cutter from Garniga fitted with a 3mm insert groover. These are stock items from Garniga. We do this on a shaper but the same heads work in a moulder. Rebated exterior jambs with the weather-strip kerf are done the same way but with a different cutter. The nice thing with this is getting the edge, radius or chamfer and kerf in one pass.

We also have a saw blade for the shaper and use that some, but it requires a separate pass for the kerfs. You probably want to do this in one shot on the moulder. Otherwise it should be possible to put a correct diameter saw blade on the moulder.

From contributor B:
Royce Air, Garniga and many others make jointing blades (square tips) in various kerfs (metric or imperial). They will bore to your specs.

From the original questioner:
I'll check into those leads... Thanks for your help.

I had thought of having a sawblade bored out, but was nervous about it spinning at 10,000 RPM. Not sure if they are rated for that speed?

From contributor B:
These manufacturers list the max rated speeds and permitted bore diameter in their specs. It depends upon the blade diameter you need. The nice thing about Garniga is they have the complete catalog online.

From contributor A:
Carbide saw blades are typically rated for 10,000. I usually run mine at 7500. A tablesaw is about 5500. At 10k the blade sings in a frightening way.

From the original questioner:
So I should put on my suit of armor, turn on the machine, and run. After the teeth have been thrown and stuck in the shop wall, I can come back and run the material. The singing will make me pucker, but should be alright, huh? Sounds like an adventure. Who said woodworking is not very exciting!

Thanks, everyone, for suggestions. Seems that with each project, I learn a little more about the capabilities of my machinery, and it always surprises me with a new product I can produce, in a cleaner, more efficient manner.

From contributor J:
Just curious what brand of moulder you have with 10000 rpm spindles?

From the original questioner:
Well, whether or not they turn at that or not, I'm not sure, but that's what it says on them. It is a dinosaur German Haller. Big, heavy, cast iron, and I love it. It probably doesn't adjust as fine or as fast as the newer machines, but it is solid. We just give it a lot of TLC, and it keeps going.

From contributor K:
We cut out the majority of the rabbet first on the table saw and leave the blade high enough to cut the kerf for the q-lon, then we run a finish cut on the shaper with a rebate head to get to final size.

From the original questioner:
Okay, I had my local machine shop (who has actually done this before) take a stock 8" 6 wing dado chipper blade and bore it out to my spindle size. Then on the other spindle, an 8" wouldn't fit, so they actually made a 6" and brazed on carbide teeth. We threw those on the moulder, got it set just right, turned it on, ran away, let it run for a sec, came back, ran material, and it worked beautifully. Really couldn't have been better. We had laminated two pieces of 4/4 together to make the jamb 2" thick (crazy homeowners looking for an "old world" look) and were able to backchannel the bottom, join one edge (in the glue up, we had flushed the other edge already) surface plane, and kerf both edges in one pass. Like I said before... The molder is old, but it works hard still and as long as we give it some TLC, it keeps going.

From contributor M:
Sounds like it worked. FYI, we use a slotting type router bit setup using a piece of jamb stock as a fence/base. We leave this set up all the time so kerfed jambs get a quick pass with the router and all done. The main reason is one pass through the moulder to profile the jamb and we are done. The bit I believe was from Courmatt.

From contributor J:
How are you doing the end rebate on your exterior jambs? Before or after the moulder?

We tried doing exterior jambs on the moulder but could never get a chip free cut easy on the end rebates after. Our process is to S4S with back out and edge easing on the moulder, the end cut on a sliding table shaper then run the long rebate and weather strip groove on the shaper.

We usually are making just a few of these at a time and sometimes only one set. We have our labor for one piece flow on these close to what a batch takes, but it still is one area I would like to improve.

From contributor M:
You may produce a lot more exterior jambs than I do. We have tried various methods ourselves and to be honest I am back to the radial arm saw for exteriors. We have used hand routers and templates and even set up the CNC router, but it was just easier and quicker to go the radial arm saw. Here is the funny part - having owned all types of radial arms saws (I don't like them), I got rid of most of them except an old Ryobi I used to use out in the field, and only very rarely at that. However, looking for a quick fix for some production jambs we were running, I brought it into the shop, and that's the machine we are using with actually good results. I believe it is an Amana dado set. We mounted the saw quite rigid but it still takes a little finesse.

Let me add some exclusions - if we are doing an interior package of rabbeted jambs or a large exterior order, we will do all mortising on the CNC router where it justifies the setup. We also currently do all of our interior jambs on the CNC, hinges, rabbet and strike all at once.

From contributor J:
I doubt we make more exteriors than you with only a 3 man shop... Your comments about the router use are interesting. I looked at door routers for 3 years and gave up the idea for now. I came to the same conclusion that it would pay for the large interior door jobs but not any faster for the one off and specialty work that is so much of our business. I still would like to own one, just glad I didnít get it this last year.

From the original questioner:
How much for a decent CNC? We do our jambs with an extremely sharp spiral bit and have had very minimal tear-out in soft maple. Just a little furring. Now fir is a different story. Especially reclaimed fir. You look at it crossed eyed and it splinters! We've tried the Amana dados on a radial arm, and it tears out too. We've just had to tell customers that want product out of reclaimed fir, vg or not, that it will be a rustic, rougher look than other material they have seen and just enjoy it for its character. Quite the sales job, huh? We've sold a lot of it for sure. Cabinets, flooring, base, casing, crown, doors, shutters.

From contributor M:
We have had our router for quite some time and it is paid for, thank goodness. Just to clarify, we do not cope and stick on the router. We use it for cutting panels, templates, beveling, and jamb work. I still to this day am not a believer that any CNC will out-produce my shapers with the same quality. We also do a huge amount of radius mouldings so you can't beat the router for cutting out solid wood blanks or the patterns to flush trim to, depending on what we are making.

As far as cost, just depends I guess on what you are looking for. There are obviously tons of good machines on the market right know with the economic downturn, so it's a buyer's market. I am still not a fan of the Chinese machines when so much other good iron is available, but that's a whole other debate. Our machine is a flat vacuum table Multicam with a 5' x 16' table. However, my first machine was a 4x8 Thermwood dinosaur that we traded a door clamp for. After new PC based controller and a lot of elbow grease, we were in the CNC game. Could never even think of going back.

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