Ricky said:
Hi Ricky,
I like to use blind fasteners so I use full cleats on my butt joints versus screws on the outside (except the rear of course). Never had much luck covering screws. When I did do that, I usually pulled the screws and filled the holes after it dried. Far too slow of a process IMHO.
A brad nailer and a couple bar clamps are my friends. Here's the inside of a plywood party speaker I did recently.
Cheers.
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Cal Weldon said:
I have used screws, with the correct size pilot hole, and had them telegraph not only through the front, but also the side. Comes through as a bump, the same length as the screw.
This is hard to discribe, and I tried to get a picture of it, but as usual my camera won't capture it. REALLY shows on a gloss finish.
For me, if glue won't hold it, I'm not doing it.
Here's a pic might show what I'm talking about:
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MJL21193 said:
*LOL*
I've never worked out if it's a 'rabbit', 'rabbet', or 're-bate'. Regardless, I don't understand what leporine beasts have to do with wood working. 😉
I was looking at making some boxes from multi sided shapes (http://en.wikipedia.org/wiki/Icosahedron) before realising that getting all the joint angles right would be loads of 'fun'. A project for the future methinks.
MJL21193 said:
Thanks. Loads of issues with it, and I'd do a second one in a very different way - but it was done as a learning exercise. It also showed me that internal angles are a pig to sand, so I'll remember that for using the technique for potential future speaker cabinets.
MJL21193 said:
Yea, MDF is very prone to splitting or showing screws if they're anywhere near the edge. If I absolutely need to use screws I'll try to clamp two flat pieces of material either side of the panel being screwed (parallel to the screw path). This sometimes helps.
Otherwise, if I need more strength, I'll usually use dowels.
BTW I've found a very useful site on MDF, and it has this to say about moisture/movement issues: http://www.mdf-info.org/using/controllingmoisturecontent.html
The info on sealing and finishing on the above site is a bit generic, but I've found the following and wondering if it might be worth a try: http://www.axminster.co.uk/product-Rustins-Rustins-MDF-Sealer-22684.htm
Wow.... I don't think I've ever spent so much time reading through every post of a 20+ page thread.
I'm very interested, as I have a few painted mdf projects coming up... although nothing as intricate as any here. Has anyone tried basic polyester resin? I know from working a little with fiberglass that the mdf soaks it up pretty well, although I'm not sure if it causes warping or expansion. I am curious about the epoxy that sploo is using. Is this epoxy resin or is it more like the extramite in powder? I imagine it's hard with the branding/naming of products in the UK vs here in the states.
I have a set of small mdf speakers that are getting primed today actaully (my gf's parents have a body shop) using automotive primer.
I haven't done any mdf painting thusfar, so I'm wondering how they'll turn out.
How is the first epoxied stack doing? I couldn't seem to find any images of that one, just the second stack. Is it still seamless?
I'm amazed at the craftsmanship of some of these builds. I've always felt silly when talking to woodworkers about using mdf for anything.
I'm very interested, as I have a few painted mdf projects coming up... although nothing as intricate as any here. Has anyone tried basic polyester resin? I know from working a little with fiberglass that the mdf soaks it up pretty well, although I'm not sure if it causes warping or expansion. I am curious about the epoxy that sploo is using. Is this epoxy resin or is it more like the extramite in powder? I imagine it's hard with the branding/naming of products in the UK vs here in the states.
I have a set of small mdf speakers that are getting primed today actaully (my gf's parents have a body shop) using automotive primer.
I haven't done any mdf painting thusfar, so I'm wondering how they'll turn out.
How is the first epoxied stack doing? I couldn't seem to find any images of that one, just the second stack. Is it still seamless?
I'm amazed at the craftsmanship of some of these builds. I've always felt silly when talking to woodworkers about using mdf for anything.
sploo said:
It's rabbet, my spelling boo-boo. 😱
That site gives an idea what we are up against with regard to moisture content. good find.
That MDF sealer is waterbased, so I can't say I'd use it on anything with a high quality finish.
I have a price back on the waterbased urethane paint - $56.00/gallon, so I'll be switching to that. I will just use solvent based urethane as the sealer, then the waterbased paint over that.
Here's the spec sheet on it:
http://www.sherlink.com/sher-link/ImgServ?id=datapages/armorseal_1k_wb_urethane_8-49.pdf
It can be tinted any colour.
spudfrog said:
More than enough MDF bashers on this forum, but here we have the talent and expertise to work with it.😉
Hi
Google MDF Powder coat
Not exactly DIY but it might be worth getting a quote for a pair of typical size boxes?
Google MDF Powder coat
Not exactly DIY but it might be worth getting a quote for a pair of typical size boxes?
pinkmouse said:
<nods in agreement>
Rabbet... who, what, when, where, why?
Its just wrong: http://www2.gsu.edu/~wwwesl/egw/jones/differences.htm
pinkmouse said:
ShinOBIWAN said:
You Brits are so stuffy. Here in Canada we, for the most part, still spell correctly.
On a totally unrelated subject, rabbet does not originate in America:
rab·bet(rbt) also re·bate (rbt, rbt) n.
[Middle English rabet, from Old French rabat, recess in a wall, act of beating down, from rabattre, to beat down again; see rebate1.]
1. A cut or groove along or near the edge of a piece of wood that allows another piece to fit into it to form a joint.
2. A joint so made.
v. rab·bet·ed also re·bat·ed, rab·bet·ing also re·bat·ing, rab·bets also re·bates
v.tr.
1. To cut a rabbet in.
2. To join by a rabbet.
v.intr.
To be joined by a rabbet.
🙂
ShinOBIWAN said:
Not really the good part. That's not fair, we owe much to the French for they were the original highly skilled craftsmen of wood. The word carpenter is derived from the French.
It would not be a stretch to say that most quality woodworking methods were pioneered in France.
Still, they are such snobs!
spudfrog said:
Some info on polyester resin coming up in my next post...
The epoxy I've been using is a West System product. It comes as a bottle of clear liquid (epoxy) and a bottle of straw coloured liquid (hardener). The two are mixed, 5:1 ratio before use.
The first epoxy stack looks just fine, as is the CD rack I posted pics of a while back. The common thing with them is that they both got really thick coats of epoxy. Unfortunately, that does make it a pain to flat, so isn't an ideal solution.
Mr Chris said:
Interesting idea. As you say, not really DIY, but it might well be worth looking into at some point in the future.
pinkmouse said:
*LOL* Remember, it's a long and proud tradition for every Englishman to kill the French 😉
OK, whilst I’ve not been posting recently, I have actually been quite busy. I've been speaking with the European Panel Federation, and one of the UK's MDF manufacturers.
The first thing that has to be said about this is that both have been extremely helpful, and considering I'm not actually buying anything directly from them, they've spent a lot of time giving valuable assistance. Two thumbs up.
Some of the docs they’ve supplied advise using polyester resin for coating in order to achieve high gloss finishes. Checking this up, I've found this is indeed a different product to the West System epoxy I've been using: http://www.westsystem.com/ewmag/22/fiberglass.html
I was going to buy some from CFS Fibreglass, but they advised against using polyester resin due to its low adhesion to MDF (I don’t have any experience with this – maybe someone could comment). I bought some Bonda G4 Sealer Varnish from them instead, on their recommendation (not tested, as it’s not arrived yet).
I spoke to Bonda who believe that urethane and cellulose paints shouldn't attack the cured sealer (no info on acrylic paints). They suggested washing and sanding the cured sealer before painting, as it can 'sweat' a chemical (I think it was something to do with the plasticiser) which could affect paint adhesion. This isn't a problem as I'd wet flat it before painting anyway.
Bonda also advised me that a method used by some galleries (to make large flat surfaces) was to join sheets of MDF at the edges, and run a 5mm chamfer along the edges. They then coat with G4, and when the last coat is tacky, they use two applications of their SuperSoft filler on the joins. Once dried and sanded back, this apparently works well.
Someone earlier in this thread mentioned a similar idea, and this may be practical if you're making a box with few joins, but for my lamination purposes it might be a little cumbersome.
As for gluing, an EPF representative advised that "PVA adhesives can be used with MDF, but for higher strength, a UF resin such as cascamite would be better. The most common binder type used in MDF is a UF rein (sic)."
I'd just started using Cascamite for gluing, so that sounds like the right route.
The info on moisture was that it is difficult to determine the precise level in composite wood based boards, so the advice about keeping it dry is largely precautionary. However, it was recommended to keep the moisture content as low as possible before finishing (something John also pointed out earlier).
What I'm wondering about doing is leaving boards/glued boxes in a room with a dehumidifier for a few days before sealing. This may help to counteract the often 'damp' British weather.
My next steps are to paint the current test blocks I’ve got (weather permitting, this weekend).
I’m also planning on ordering some urethane paint, and trying a Cascamite glued, G4 sealed, urethane painted, test in the near future.
The first thing that has to be said about this is that both have been extremely helpful, and considering I'm not actually buying anything directly from them, they've spent a lot of time giving valuable assistance. Two thumbs up.
Some of the docs they’ve supplied advise using polyester resin for coating in order to achieve high gloss finishes. Checking this up, I've found this is indeed a different product to the West System epoxy I've been using: http://www.westsystem.com/ewmag/22/fiberglass.html
I was going to buy some from CFS Fibreglass, but they advised against using polyester resin due to its low adhesion to MDF (I don’t have any experience with this – maybe someone could comment). I bought some Bonda G4 Sealer Varnish from them instead, on their recommendation (not tested, as it’s not arrived yet).
I spoke to Bonda who believe that urethane and cellulose paints shouldn't attack the cured sealer (no info on acrylic paints). They suggested washing and sanding the cured sealer before painting, as it can 'sweat' a chemical (I think it was something to do with the plasticiser) which could affect paint adhesion. This isn't a problem as I'd wet flat it before painting anyway.
Bonda also advised me that a method used by some galleries (to make large flat surfaces) was to join sheets of MDF at the edges, and run a 5mm chamfer along the edges. They then coat with G4, and when the last coat is tacky, they use two applications of their SuperSoft filler on the joins. Once dried and sanded back, this apparently works well.
Someone earlier in this thread mentioned a similar idea, and this may be practical if you're making a box with few joins, but for my lamination purposes it might be a little cumbersome.
As for gluing, an EPF representative advised that "PVA adhesives can be used with MDF, but for higher strength, a UF resin such as cascamite would be better. The most common binder type used in MDF is a UF rein (sic)."
I'd just started using Cascamite for gluing, so that sounds like the right route.
The info on moisture was that it is difficult to determine the precise level in composite wood based boards, so the advice about keeping it dry is largely precautionary. However, it was recommended to keep the moisture content as low as possible before finishing (something John also pointed out earlier).
What I'm wondering about doing is leaving boards/glued boxes in a room with a dehumidifier for a few days before sealing. This may help to counteract the often 'damp' British weather.
My next steps are to paint the current test blocks I’ve got (weather permitting, this weekend).
I’m also planning on ordering some urethane paint, and trying a Cascamite glued, G4 sealed, urethane painted, test in the near future.
sploo said:
Hi Sploo,
This is really a very good idea. I didn't think of this, but should work well. I have one sitting in my basement unused since it's no longer damp down there (finished it last winter).
May put it in my "lab" where I tinker with electronics and use this room as a "dry room". Speed up the process.
Fantastic work Sploo. I'm glad I started using Extramite now 🙂
Looking forward to the results of the next block test. I'm kind of hoping the dehumidifier can be avoided as that's a thing I just don't have the money or space to have such a luxury.
Looking forward to the results of the next block test. I'm kind of hoping the dehumidifier can be avoided as that's a thing I just don't have the money or space to have such a luxury.
MJL21193 said:
Naah, ship it to me instead 😉
I took a look at the prices of a few models, and they're about twice what I thought they cost
richie00boy said:
Well, today I painted the current test blocks.
On checking the blocks, and performing final flatting, I discarded the PVA glued/varnish coated and the PVA glued/HS primer coated blocks, as both were showing signs of sinking along the glue lines.
The three epoxy coated blocks were harder to flat, as the epoxy cures very tough. The varnish and HS primer flats nicely. All done wet with P400.
I ran out of the cellulose paint I've got, but just managed to spray four coats on the blocks. I would have preferred a few more.
No sinking on the glue lines was apparent immediately after spraying (which I did see with a previous epoxy coated block).
I'll let them dry for a few days, flat, the drop some clearcoat on them.
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