Cutting through MDF with a router - Router Forums
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post #1 of 17 (permalink) Old 07-31-2016, 04:40 AM Thread Starter
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Default Cutting through MDF with a router


I have access to a Ryobi cordless trim router and two plunger routers – one is a WorkZone and the other I can't recall at the moment (it's not at my place).

I have used the trim router several times to smooth edges but have never used any of the plunge routers, and so obviously I'm very inexperienced at routers in general.

I currently have a sheet of 16mm MDF which will be a counter top with a gas stove top inserted in it. The counter top is already cut to size and the cut out for the stovetop has been cut out – I rough cut it with a jigsaw then finished it off with the trim router running against a straight edge. No problems with any of that – perfect fit and looks good.

However the stovetop specifications are that the bench top be between 30 and 40 mm in thickness, so I am mounting another 16mm sheet under the above. It makes sense to me to use the top already prepared sheet as a template to remove the cutout in the second sheet.

My question:

Seems to me the easiest way to duplicate the cutout would be with a router, using the top cutout as a guide. But I will have to plunge into the MDF and I have never tried to cut timber before with a router. Is this a good approach? Any tips or warnings?

The Ryobi trim router is light and I am at least somewhat used to operating it. Can it do this job or will I have to use one of the plunge routers?

Any advice much appreciated.
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post #2 of 17 (permalink) Old 07-31-2016, 05:01 AM
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welcome to the forums Bill...

here's a little something that help you in your endeavors...

rough cut like you did on the original cut out w/ the jigsaw...
use a top bearing trim bit to match your cut out...
Freud Tools | 1/2" (Dia.) Top Bearing Flush Trim Bit

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File Type: pdf Routing for beginners - Lesson - 5.pdf (4.36 MB, 186 views)
File Type: pdf ROUTER FEED DIRECTION 5.pdf (54.6 KB, 183 views)

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post #3 of 17 (permalink) Old 07-31-2016, 08:49 AM
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"Any advice much appreciated."
************************************************** *****
You'll burn out the trimmer cutting 35 mm MDF.
This has to be done in stages with a plunge router with at least 1 HP.
Cut as close as you can with collars, finish with trimmers (cutters with bearings).
In will create willlies that you've never seen before, toxic, messy, something you can't clean up. The best of vacuums can't keep up with the waste.
Do this outside (outback!) with face protection.
Use only carbide.
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post #4 of 17 (permalink) Old 07-31-2016, 08:58 AM
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Do you need a single piece sheet below? Usually we use scraps about 2" wide. Glue them to the bottom of the counter in the shape of the hole. No router needed at all.

Last edited by Everend; 07-31-2016 at 09:07 AM.
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post #5 of 17 (permalink) Old 07-31-2016, 10:20 AM
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Welcome to the forum Bill. We have lots of members from Oz among us. Routers are a poor tool for removing lots of material. They do best at profiling and cleanup. As suggested rough cut to close and use the trimmer to finish.

Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.
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post #6 of 17 (permalink) Old 07-31-2016, 10:43 AM
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To give the extra strength for a counter top I'd cut a second peice just 2-3mm wider and longer than the first. Lay it underneath and clamp. draw round where your sink will go using the first as the template. Remove first sheet, cut most of sink hole out with jigsaw, then replace first and use a bottom bearing template/pattern bit to clean up. Once the holes are completed, and while the two are clamped together, use the bottom bearing template/pattern bit to match width and length. When using the plunge router, just line up the bearing with the first thickness of mdf and the cutter will cut the second to match.
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post #7 of 17 (permalink) Old 07-31-2016, 03:52 PM
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Hi Bill. I think everyone has you pretty much covered as to the proper method to accomplish this,but I didn't see anyone mentioning a dust mask. Use the best one you can... the dust from MDF is so fine it will kill you.


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post #8 of 17 (permalink) Old 07-31-2016, 07:01 PM
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Firstly, Bill, welcome to the forum.

Secondly, what Stick said....

I work outside, so the dust just blows away, but if you work indoors, what Brian said.... MDF dust is dangerous....

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post #9 of 17 (permalink) Old 08-01-2016, 10:44 PM Thread Starter
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Thanks very much guys. The purpose of my original question was basically to see if I could skip the jigsaw step and, using the sheet with the hole already cut out as the template, cut & trim in the one operation with the router.

Y'all didn't seem to like that idea too much so I took your collective advice and again did the jigsaw thing first. Job is now finished and still looking pretty good.

Certainly glad I found you guys – lots of good information provided. Just hope I don't get ahead of myself as this router gadget is giving me all sorts of ideas that are probably well beyond my capabilities at the moment :-(

Anyway, I've still only use the Ryobi cordless trim router, so I guess it might be wise to find a project where I can get a bit of practice with the plunge routers. I was thinking that a DIY router table might be a very handy addition to my slowly growing workshop. I have been looking through YouTube, but so many to choose from I'm having trouble making a decision.

Just a few comments...

Stick486: Thanks, I really appreciate the list of PDFs. I've printed them all and will work my way through them.

Quillman: I would have only been cutting 16mm MDF sheet, not 35mm. The benchtop now consists of 2 x 16mm sheets, one atop the other, but your warning is noted. Yes, my first encounter with routing MDF alerted me to the dust dangers. I have a good multi-filter Protector Respirator.

Everend: I must admit I didn't even think about using scrap pieces instead of a full sheet. Anyway, it's measured cut and done now.

Again, thanks to everyone for your help.
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post #10 of 17 (permalink) Old 08-01-2016, 11:20 PM
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I tried MDF once. Did NOT like it, and have never used any since. Nasty stuff as far as I'm concerned.
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