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Forum topic by mortalwombat posted 09-19-2015 01:31 AM 755 views 0 times favorited 14 replies Add to Favorites Watch
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mortalwombat

65 posts in 1614 days


09-19-2015 01:31 AM

Topic tags/keywords: mdf tongue and groove joint cabinet router router bit

So I have a bunch of high grade laminated MDF that was given to me, and I’d like to use it to build my shop cabinets. I am going to build it based on this idea.

On the rolling cabinets, I was hoping to use 1/2” MDF for the side panels, and 3/4” on the top. I was going to use tongue and groove construction, especially where two boards T together. But my tongue and groove router bit cuts 7/16” deep. That won’t leave much material left. Here is an example from the plans I am working on.

Is there a better way to do this? I don’t have a dado blade for my TS yet, so I’ll have to do most of this work with a router.


14 replies so far

View lateralus819's profile

lateralus819

2236 posts in 1356 days


#1 posted 09-19-2015 01:34 AM

Could just do the dado’s with a normal blade. Would take a while but its do-able. I’ve done it a lot.

View Yonak's profile

Yonak

979 posts in 988 days


#2 posted 09-19-2015 02:40 AM

wombat, I have a few questions : Can’t you adjust the depth of cut for your router ? Can you do it on the table saw, instead ? It looks like Bill Endress doesn’t use dados. Could you go with blocks under the shelves attaching with glue and screws, instead ? Speaking of glue and screws, could you attach with screws from the outside and cover with plugs or a wood strip either attached as a cover or inset (oh, that’s right, if you can’t make dados less then 7/16” deep, the inset idea wouldn’t work). Would you rather not mess with trimming the shelf edges and just make the dados the width of the shelves ? Do you think 1/2” is stout enough for the cabinet sides ? ..Just a few questions for you to consider while designing your plan.

View mortalwombat's profile

mortalwombat

65 posts in 1614 days


#3 posted 09-19-2015 04:23 AM

I suppose I could adjust the depth with a fence on the router table, but I love the speed and accuracy that the tongue and groove bit provides. I could definitely do screws from the outside, but it’s a really nice veneer that I would love to keep clean. I like the idea of doing the dado the width of the shelves. I have a router bit that would make that easy except the material is slightly thicker than 1/2” with the veenery (probably closer to 9/16) so I’d have to find a way to adjust for that.

The biggest thing is that I am going to have a lot of joints so being able to get accuracy while being efficient is going to be key for this project. Repeat cuts to create a dado on the table saw is less than ideal for that reason. I also want to have nice tight joints so that it’s durrable. Because I am using MDF instead of plywood, I worry about it standing the test of time.

As I sit here, however, I realize I can probably come up with a method for making fast and repeatable tongue and groove with two routers. A straight bit in the router table and a rabbeting bit in the handheld router.

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canadianchips

2360 posts in 2464 days


#4 posted 09-19-2015 10:51 AM

7/16 groove into 1/2 MDF material is NOT a good idea. MDF is weaker than ply core to start with. That groove will just weaken your side panels.

-- "My mission in life - make everyone smile !"

View rwe2156's profile

rwe2156

2198 posts in 948 days


#5 posted 09-19-2015 11:54 AM

Do a shallow full width dado I would use screws as my experience edge gluing MDF is not strong enough. You can screw from the bottom at an angle from the inside (while clamping together of course).

MDF is nasty material to work with. It produces the finest of dust and is loaded with formaledhydes and other noxious chemicals. With the addition of laminate, you can add the chemicals related to that.

MDF requires scrupulous attention to protecting your lungs. Full face respirator with a gas filter as well as some kind of dust control measures. Be prepared for the stuff to get all over everything unless you have excellent dust control.

-- Everything is a prototype thats why its one of a kind!!

View markum's profile

markum

6 posts in 685 days


#6 posted 09-19-2015 12:24 PM

I do agree with rwe2156 on the dust issue. In defense of the material however, I Have made numerous raised panel cabinets using various colonial templates. I do admit that when it came time to doing the router cut, I wore my respirator and had the shop windows and doors open with the central vac on. The end result however (now these are painted cabinets) was great. The ones I made for myself have been in use for over 10 years and they look new. I admit though I did not use the product stand alone. All cabinets had poplar styles and rails and the shelf attachment, in many cases pin supports, were done in the poplar. Not a good idea to have a shelf inset into a side panel with only 1/16th left in the panel. If your case were to shift even a little so your unit was less than perpendicular to the floor or whatever, there will be a lot of “cracking” and “snapping” as each grove breaks open.

View Daruc's profile

Daruc

459 posts in 599 days


#7 posted 09-19-2015 01:53 PM

I would make a shallower dado the width of the shelf, and I wouldn’t tongue the shelf. Leave it full thickness.
The mdf likes to split easily and the shoulders on the tongue give it a place to start splitting making for a weaker joint.
Lots of glue, don’t be stingy.

-- -

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johnstoneb

2148 posts in 1640 days


#8 posted 09-19-2015 02:04 PM

If the cabinets are stationary the MDF will work very well. For the rolling cabinets There is a lot of sideways stress. You need to build an internal frame to reinforce the joints. MDF does not handle lateral forces well.

-- Bruce, Boise, ID

View Yonak's profile

Yonak

979 posts in 988 days


#9 posted 09-19-2015 04:51 PM


I would make a shallower dado….

- woodust

The issue is his router cannot be adjusted to make shallower dados.

wombat, I think the solution is either to get a new router or a dado blade for the table saw. Also, I don’t think 1/2” is enough thickness for side walls.

View Daruc's profile

Daruc

459 posts in 599 days


#10 posted 09-19-2015 05:40 PM

Maybe I’m not picturing it, but I figure you could put a spacer under the plate, or in between there somewhere?
A little thinking outside the box may be in order.
(Buy a new router bit)

-- -

View mortalwombat's profile

mortalwombat

65 posts in 1614 days


#11 posted 09-19-2015 05:57 PM

I will take all the advice being given here. Tongue and groove is out, Dado is in. I have a 1/2” router bit that will do the job nicely, but it’s going to be 1/16” too tight because of the laminate. So I will have to cut the laminate off to match the dado. And I will add a backing strips of some sort where I can to strengthen it up, and face frame it with some real wood. This is the modified version of the picture above, dark colored areas being real wood.

Regarding the dust issue, I plan to wear a respirator and work outside. My dust collection is admittedly crummy, and I’ve heard tons about how terrible MDF dust is. Dust collection is slated to be my next project, once all my tools have a good solid home. For now it’s a shop vac with a 5 gallon bucket as a separator. It pretty much just lessens the amount of cleanup I have to do, but does very little for my lungs.

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Yonak

979 posts in 988 days


#12 posted 09-19-2015 08:53 PM

You could make two passes with the dado bit (one forward and one reverse, that will trim up both edges very nicely) to make the dado the right width instead of trimming the laminate.

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mortalwombat

65 posts in 1614 days


#13 posted 09-19-2015 08:57 PM

I like that idea. It means adjust the fence twice for every dado, but that’s reasonable to get a nice clean joint.

View Daruc's profile

Daruc

459 posts in 599 days


#14 posted 09-19-2015 09:40 PM

If it’s only the thickness of the laminate,
take a strip of laminate and put it against your fence, make a pass, remove the strip and make your second pass.

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