MDF Mitres - Should I domino?

[bigfella]

Hi Guys,

Need to build a couple of toy boxes around 1000mm x 600mm x 600MM. Planning to use 18MM MDF with mitred edges. They will be painted in a gloss and I don't want any of the joints to be visible.

Was planning to use dominos/glue/clamps.

Is that the best approach? Read a few posts saying that dominos can be a pain and it is best to use tape and fold.

Thanks,

Ash

 

[tjbnwi]

Align on tape, glue, fold, check square.

Dominos can be a pain in beveled box sides.

Other choice is lock miter bit.

Tom

 

[Bohdan]

Used to do a lot of this. I used aluminium angle along the full length of the corners to align them. The pressure was supplied by steel packaging straps but you could use any strapping to hold the angle in place and then clamp with regular bar clamps. Wax the aluminium to prevent the glue that will squeeze out from sticking them to the job.

 

[dltflt]

Other choice is lock miter bit.

Tom
[/quote]
Now that is a pain in my opinion.

 

[tjbnwi]

Other choice is lock miter bit.

Tom

Now that is a pain in my opinion.
[/quote]

A breeze with this/these;
http://www.infinitytools.com/2-Pc-Lock-Miter-Master-Jig-Set-For-3_8-1-3_16-Stock/productinfo/00-LMM/

Tom

 

[bigfella]

Do you need a router table to use a locked mitre bit? I only have a OF1400, but not a table (yet). Also, looks a bit complicated for a couple of MDF toy boxes.

I like the aluminium angle and tape ideas. I have a heap of ratchet straps so could use those to keep it tight while the glue sets.

I was originally thinking dominos to help with alignment and strength, but seems like they will be problematic.

 

[#Tee]

any reason why you want to miter since its going to be painted in gloss? theres no grains to hide or a profile to line up? why not just domino with regular square cuts? glue/spackle/prime and paint. 

 

[ajones]

any reason why you want to miter since its going to be painted in gloss? theres no grains to hide or a profile to line up? why not just domino with regular square cuts? glue/spackle/prime and paint.

Better still rabbit the corners for a virtually  invisible joint which will help keep the whole thing square..

 

[Master Carpenter]

I would lock miter, but that's just because mine is set up in the table right now in my shop.  If I was doing it on site and I wanted to simplify alignment, I'd probably do a splined miter.

Domino would be one of my last choices.

 

[Roseland]

Do you need a router table to use a locked mitre bit?

Absolutely.  I used to wonder why until I bought such a bit and built a table.  I can now see that if the bit dug in it could throw the router out violently.  And for good results you need the stability of a table.

Andrew

 

[bigfella]

any reason why you want to miter since its going to be painted in gloss? theres no grains to hide or a profile to line up? why not just domino with regular square cuts? glue/spackle/prime and paint.

I was going to do a regular butt joint with dominos and brads but was concerned I would see the join through the paint. You don't think that will be a problem?

 

[ear3]

The beauty of MDF and spackle is that all those can be filled in and smoothed out prior to painting.  No one will be the wiser.

any reason why you want to miter since its going to be painted in gloss? theres no grains to hide or a profile to line up? why not just domino with regular square cuts? glue/spackle/prime and paint.

I was going to do a regular butt joint with dominos and brads but was concerned I would see the join through the paint. You don't think that will be a problem?

 

[rvieceli]

Try a test piece first with the butt joint. You don't have to make the entire box just one small piece of corner.

 

[Holmz]

I would totally be doing this with some mitre/finger... But if they move, then why not make be able to some apart?

 

[#Tee]

any reason why you want to miter since its going to be painted in gloss? theres no grains to hide or a profile to line up? why not just domino with regular square cuts? glue/spackle/prime and paint.

I was going to do a regular butt joint with dominos and brads but was concerned I would see the join through the paint. You don't think that will be a problem?

a miter will still show and leave a butt joint until its painted

 

[junk731]

Keep life simple, do your miters, using blue stretch masking tape and precheck your joint is square/tight. Then glue the joint, check for square. The joint can be adjusted easily with the tape. We've been doing these joints for years on all types projects without problems. Works great on MDF because its all saw dust and glue away.

John

 

[JCLP]

I use dominos all the time for mitred corners. Once you get the hang of it, it's quite quick and simple. If your mitres are close to a perfect 45 degrees, then glueing up is a breeze. In the photos below I used #4x20mm dominos. The last photo is not glued.
Cheers,

 

[dltflt]

Other choice is lock miter bit.

Tom

Now that is a pain in my opinion.

A breeze with this/these;
http://www.infinitytools.com/2-Pc-Lock-Miter-Master-Jig-Set-For-3_8-1-3_16-Stock/productinfo/00-LMM/

Tom
[/quote]
I've looked at those several times and wondered if they actually worked. Thanks Tom.

 

[Birdhunter]

I'd use a spline approach for the mitered sides especially with MDF. I've never had much success with Dominos on mitered joints. They are really fussy as are lock miters.

I set the table saw for 45 degrees and cut the sides. I leave the saw at 45 degrees and adjust the cutting depth for the spline cuts. I use 1/8" aviation grade plywood for the splines. For MDF, I'd apply a thin hardwood layer to the exposed parts of the box to protect the MDF, hide the splines, and dress up the look.