Woodworking Rant

[DeathMonk]

I make the most precise cuts. Throw out and peices that are even slightly off.

I start gluing a sub together last night that I am working on and notice that things are a little off (overhangs).

I measure the MDF and its almost 1/16" wider than 3/4". Same with the 1/2" I bought. The MDF that I bought for my last project was exact, only it was bought at lowes vs. home depot for this stuff.

It's things like this that really annoy me. It's already hard enough to get things perfect when gluing together boxes.

Also, I glued the bottom, side and middle brace last night on the sub. I held a square to the bottom and side and it was perfect. Come out this morning after it had dried and now its almost 1/8" off at the top.

Does this happen to anyone else, or am I just the suck at woodworking?

[LuncHwagon]

MDF is usually pretty uniform in thickness. Moisture content can make it swell. I dont know your situation. I will tell you that most woodworkers will tell you that making something PERFECTLY square, is one of the most difficult things to do. I've found that in speakerbuilding, I am a friend of the Flushtrim bit.

[Txgrizzly]

DeathMonk, i have been doing woodworking for a while now and i always double check the sheet goods i get. i have actually had two peices of plywood that came out of the same pile (sheets where right on top of each other) that were almost 1/8" in difference. it bites when you are trying to get joints to fit tight. about the box shifting during glue up, that happens sometimes when you have a slight sideways pull on your clamps and the glue joint will slip with the pull... glue is very slippery until it starts to tack so you have to make sure there is no slipping usually for the first 30minutes or so. also try to make sure you clamps are as square as the can be to your glue joint or they will try to pull the joints...

And yes it sucks royally ;(

[DeathMonk]

Maybe it's the moisture.. It's been really humid lately.

I know that in woodworking, there is always ways to make something look good/work.

It's just really frustrating when you're a perfectionist

[JonMarsh]

Suggest getting a good steel rule at a place like Woodcraft, with 1/32 and 1/64 marking, and check things as you go along.

I'm in Northern CA, never have had problems with 3/4" MDF or 1/2" MDF being "off". But they use different suppliers from time to time, and I always look at what I buy closely. Here, it's the Lowe's that blow major league.

[DeathMonk]

Suggest getting a good steel rule at a place like Woodcraft, with 1/32 and 1/64 marking, and check things as you go along.

I'm in Northern CA, never have had problems with 3/4" MDF or 1/2" MDF being "off". But they use different suppliers from time to time, and I always look at what I buy closely. Here, it's the Lowe's that blow major league.

Yeah,

Next time I buy some MDF, I will grab a ruler in the tools section beforehand

[john trials]

I'm currently building some Statements.

I glued and clamped my MDF using two 90 degree precision aluminum brackets that are perpendicular to 0.003". They are normally used for precision optical assemblies. The brackets remained clamped in each glue joint overnight (I work slowly!). I use Titebond II.

https://www.thorlabs.com/thorProduct.cfm?partNumber=VB01#ad-image-0

Image not avaialble

In the end, the top of my cabinets were off by about 3/32" to 1/8" from perpendicular (this happened with both of my cabinets). I ended up covering the entire top with bondo to level the top. Then I covered the bondo with another 3/4" MDF board. My cabinet is nice and orthogonal now...it's just 3/4" taller than planned. Luckily the baffles and rear panels I cut are oversized (by 2 inches in height), so I didn't have to make new panels.

I'm still not sure why the pieces didn't remain perpendicular when unclamped. I wished I had used some temporary bracing that could be removed just prior to finishing the cabinets.

[LuncHwagon]

Maybe it's the moisture.. It's been really humid lately.

I know that in woodworking, there is always ways to make something look good/work.

It's just really frustrating when you're a perfectionist

Ive found that woodworking and perfectionism dont go well together. Only "Nawm" is able to make ALL his joints work the first go-round. Thats why he has long running show. Its like magic.

[Txgrizzly]

Another thing that can help is as you are gluing up the sides, bottom and top of your speaker if you already have your rear panel and baffle cut to size wrap some cellophane (Saran Wrap) on the edges and slid them into place. This will help keep your box square and they won’t get stuck in the box if glue hits them. to make this work though you have to make sure your back panel and your Baffle are square ofcourse...

[john trials]

Ive found that woodworking and perfectionism dont go well together. Only "Nawm" is able to make ALL his joints work the first go-round. Thats why he has long running show. Its like magic.

True!!!! I machine aluminum for scientific/optical products. I'm used to precision at work. Wood is a new material for me...MDF is a fairly nice wood product, though. Uniform density, no grain, smooth, fairly flat.

It has been hard for me to accept the fact that my cabinets are not going to be perfect!

[---k---]

My initial thought when I read his post was that it was a metric vs. imperial thing. If you notice, a lot MDF is not 4'x8' like plywood. It is like 2" bigger. The thickness is also usually off a little too, but it is close.

[DeathMonk]

not true.. The last MDF I had was only in the 100ths of an inch off.

[wackii]

I'm currently building some Statements.

I glued and clamped my MDF using two 90 degree precision aluminum brackets that are perpendicular to 0.003". They are normally used for precision optical assemblies. The brackets remained clamped in each glue joint overnight (I work slowly!). I use Titebond II.

http://www.thorlabs.com/thorProduct.cfm?partNumber=VB01

http://www.observedtrials.net/otn4/clamps%20(Large).JPG

In the end, the top of my cabinets were off by about 3/32" to 1/8" from perpendicular (this happened with both of my cabinets). I ended up covering the entire top with bondo to level the top. Then I covered the bondo with another 3/4" MDF board. My cabinet is nice and orthogonal now...it's just 3/4" taller than planned. Luckily the baffles and rear panels I cut are oversized (by 2 inches in height), so I didn't have to make new panels.

I'm still not sure why the pieces didn't remain perpendicular when unclamped. I wished I had used some temporary bracing that could be removed just prior to finishing the cabinets.

The glue makes the pieces sliding off unless you have good corner clamps to hold them down well. This happened to me before. I've learned my lesson by checking my gluing baffles every couple mins to make sure they're not sliding off. Also, it helps if you place some heavy objects right next to your baffles to keep them from sliding either sides... On my first diy sub, I used glue and screws to joint all the sides together cuz' at that time I only have 2 clamps (still dont have enough now). That works pretty well. Just take more work on pre-drill those holes.

Al,

[DeathMonk]

I've done those things before too. Nothing is foolproof, though.

[cjd]

True!!!! I machine aluminum for scientific/optical products. I'm used to precision at work. Wood is a new material for me...MDF is a fairly nice wood product, though. Uniform density, no grain, smooth, fairly flat.

It has been hard for me to accept the fact that my cabinets are not going to be perfect!

MDF is a fairly CRAP material for a huge number of things - like concrete, it's not bad in compression strength. It has really poor shear strength and joints are also generally simply adequate (it's excessively easy to tear-down a speaker box made in MDF - far less so one done with birch ply or similar). But I can see how a machinist would love it.

You CAN be a perfectionist with wood. However, you must BE like wood - that is, flexible. You work with grain - not beat it into submission.

Having spent a lot of time in the metalshop, I have realized that machinists often don't have a feel for the material they use - they just want it to obey. Ask one to hit it till it's almost-but-not-quite broken, blindfolded. I was doing a "documentary" (for a school project) on the glass studio and was filming someone making a pitcher - it was nearing the end and I commented "you're waiting too long, it's gonna crack" - guess what... it did. Of course, don't ask me to suggest feed rates for machining. Different understandings of the material, really.

If you want to work this (the "machinist") way, invest in a biscuit jointer. It's the tool you're missing.

C

[PoorboyMike]

If you want to work this (the "machinist") way, invest in a biscuit jointer. It's the tool you're missing.

C

A biscuit joiner eh? I've been considering one of these for a while now but have seen others post that they are not needed. Needed or not, it sure seems like it would help 'cause I have a hell of a time getting anything square on my glue ups. :M

[Rolex]

Ive found that woodworking and perfectionism dont go well together. Only "Nawm" is able to make ALL his joints work the first go-round. Thats why he has long running show. Its like magic.

actually some of his joints are far from perfect. and he experiences a lot of chip out that does not have to be.

[JonMarsh]

If you want to work this (the "machinist") way, invest in a biscuit jointer. It's the tool you're missing.

C

Some of us DO have biscuit jointers (technically, a Plate Joiner, DeWalt DW682- it's a honey!) and do use them- naturally to be "featured" in the skilled hands of ET for building the Ardent.



I know, I know, more tool porn....

Hello, my name is Jonmarsh, and I am a tool addict... or addicted to tools, take your pick.

[LuncHwagon]

You CAN be a perfectionist with wood. However, you must BE like wood - that is, flexible. You work with grain - not beat it into submission.C

I'm anticipating a "wax on, wax off" lesson here.
Getting a biscuit jointer MIGHT help you out. So might dadoes. The key is properly calibrating your tools and knowing how to use them. I cut some ministatements with dadoes. The boxes ended up being square to about a 32nd...im guessing if i screwed it tight, it would have been better.

[LuncHwagon]

I know, I know, more tool porn....

Hello, my name is Jonmarsh, and I am a tool addict... or addicted to tools, take your pick.

This is really funny on multiple levels

[Bill Schneider]

Heh, I have a biscuit jointer and made a jig to make sure material is held square (and the jointer itself WAS off from the factory), but STILL have trouble getting things perfectly square when glued up.



Thank goodness for 80 grit sandpaper to mitigate errors!

And a big rubber mallet when clamping.

[kingpin]

If they stand up-right...they are square enough.

[cjd]

If they stand up-right...they are square enough.

That's the spirit!

[Hdale85]

What happened to the days of bare MDF speakers with wood filler all over them and pencil markings? If you ask me there are far to many "finished" cabinets around here these days! You people make me sick with all your free time :B

[tomdro]

Wood, including MDF, is a very forgiving material. The test of a true craftsman is how well you can hide your mistakes.

[chrismercurio]

I have had mdf, bb ply, and various other grades of birch ply all be a little under/over the thickness they were supposed to be. You only get into trouble when you don't measure the stock thickness before you buy, or before you cut. It sucks and I have been there more times than I care to remember.

I second Jon's recommendation for some quality steel rules from woodcraft and a few eng. squares to go with them. Indispensible.

[Txgrizzly]

what Tomdro said....

[RobP]

Always use a nice caliper to measure your stocks thickness, much more accurate than a ruler. Do that and make sure you use those exact measurements in your plans and your work will turn out perfect.

[DeathMonk]

I know, I should have measured the thickness first

I was thinking about investing in a biscuit joiner but I've found a method that seems to work pretty well...

Bead your glue, line up the joint on one end then shoot a brad nail. do the same on the other end and then clamp. It comes out really good most of the time (as long as you account for your material thickness) ;P

[cjd]

I think a lot of us still cut a little proud and flush-trim things into shape.

[Brian Walter]

I was reading on one of the woodworking forums the other day that someone else found MDF to be off in thickness and I think it was determined that it was a metric dimension of 20 mm (0.787"). So my guess is that you also found a metric sheet of MDF.

Brian Walter

[Dennis H]

Also, I glued the bottom, side and middle brace last night on the sub. I held a square to the bottom and side and it was perfect. Come out this morning after it had dried and now its almost 1/8" off at the top.

Wood is pretty flexible compared to metal. As long as your length dimensions are correct and your cuts are square, you can square the box up and straighten any warped panels when the front and back go on. You might need some clamps to get it racked into shape.

Edit: about the glue being slippery, a hammer (or rubber mallet) is your friend. Tighten the clamp just enough to squish the glue out, tap the panel into place and finish tightening the clamp. Move on to the next clamp and repeat.

[DeathMonk]

I got the other side glued last night and went out there this morning to test fit the baffle. What do you know... Perfect (enough).

[shame302]

Perfect enough is right. The time and precision required to make it perfect usually isn't worth it. A specially if you are re-popping parts and scrapping not-so-perfect parts that could probably be used. Generally with the naked eye you cant see those imperfections and if you think far enough ahead and make use of a flush trim bit they will look perfect. By the time things are sealed, filled in, sanded/prepped and covered/laminated those tiny imperfections are gone. With the acceptation of mirror gloss piano black.

Plus if if you test them before you finish them, half the time they don't get finished. Mine are still rockin' the MDF look. I can't seem to find it in me to deal with the down time.

[1Michael]

I gave up on square boxes looooong ago. Now I just slap them together and then cut the tops and bottoms to fit whatever shape the box is :rofl:

[bemis23]

Perfect enough is right. The time and precision required to make it perfect usually isn't worth it. A specially if you are re-popping parts and scrapping not-so-perfect parts that could probably be used. Generally with the naked eye you cant see those imperfections and if you think far enough ahead and make use of a flush trim bit they will look perfect. By the time things are sealed, filled in, sanded/prepped and covered/laminated those tiny imperfections are gone. With the acceptation of mirror gloss piano black.

Plus if if you test them before you finish them, half the time they don't get finished. Mine are still rockin' the MDF look. I can't seem to find it in me to deal with the down time.

Yippee, my upcoming project is going to sporting mirror gloss piano black. fortunately, I'm not just a perfectionist....I'm basically OCD. If I finish it and see something is off I'll completely resand it and start over.

[Hank]

Actually, good quality MDF is made with precision machinery. The slurry is compressed under high pressure and heat down to precise finished thickness. I've bought probably close to a hundred sheets in the last 20 years and have had none over or under the nominal thickness. Maybe I've been lucky. I can see that MDF may swell a tad if exposed to a high humidity environment. As Brian noted, I think you got hold of metric MDF.
Regarding biscuits, I put them in the same category as nails and screws: Not Needed. I always advise newbs that nails and screws (and biscuits) do not add to cabinet strength. Modern glue, applied to accurately cut wood (MDF) will result in a glue joint that is stronger than the wood. If I'm building a large cabinet, I'll use my brad nailer (Jon, insert a brad nailer porn pic here) sparingly to hold panels together after gluing, to make applying clamps easier. I apply Merle band clamps, then parallel jaw clamps and have a square cabinet.
http://www.mlcswoodworking.com/shops...rle_clamp.html All that said, I do like Kingpin's attitude! :T

[dlr]

I know, I should have measured the thickness first

I was thinking about investing in a biscuit joiner but I've found a method that seems to work pretty well...

Bead your glue, line up the joint on one end then shoot a brad nail. do the same on the other end and then clamp. It comes out really good most of the time (as long as you account for your material thickness) ;P

I don't have much for a shop, but worked out a way that keeps things reasonably square. I bought a biscuit joiner, but dropped it when it didn't work out as well as what I now do.

I cut the mdf for all pieces slightly over-sized, then use a router table with a straight cut bit to make all edges perfectly (enough for me) flat and also to the precise dimensions. This includes certain ones that are about 2mm long (top and bottom pieces as I do it) for 1mm overhang so that I can trim them with a router after assembly. The sides pieces, rear baffle and front baffle (or purchased baffle from Parts Express) are sized to the precise dimensions. The router table makes precise depth of cut easy as well. The top and bottom (oversized for all but the driver baffle side) are rabbeted using a router. Again, perfectly flat and vertical cuts.

The box will stand fully assembled, unclamped and unglued if the fit is good.

When I glue the sides to the bottom first, I clamp with the unglued front and rear baffles in place. This makes for a nice, tight seat for the baffles. The top is glued in the same fashion usually next and the baffles are done last, but I've done the back before the top as well. Straight clamps are used as needed to pull things together for alignment for each gluing step. Band clamps worked in the right situation as well.

The key is cutting the sides, front and rear baffles square to start.. That to me is the more tricky part. Of course the rabbets were cut after verifying the depth. I've got mdf left over from my time living in Quebec where the mdf was 20mm. I've had 19.5mm here as well as the more common 19.0. Slightly over-sizing for later router trim definitely makes things easier.

Dave

[AvFan]

I'm a long-time woodworker but a first-time speaker builder. As others have mentioned I check my sheet goods for uniform thickness and try to cut any parts that fit into dados from the same sheet.

For the bookshelf MTMs I'm building I cut 1/4" wide dados in the top and bottoms to receive 1/4" tabs milled into the ends of the sides. I did this to help alignment during glue up versus strength. I've used biscuits before but I wanted a little more time to get the cabinet square than biscuits provide. The biscuits expand very quickly after they come in contact with the glue and limit any adjustments. With a dado and tab there won't be any slipping from fresh glue that you might get with a butt joint.

Like dlr, to keep the cabinet square I cut a 1/4" rabbet on the inside face of the back and front baffle to the inside dimensions of the cabinet and used it to align the sides, top and bottom during assembly. I use a little wax paper on the baffle at the cabinet corners to keep from gluing it to the cabinet. I suggest gluing the sides, bottom, top and any braces at one time to keep the cabinet as square as possible.

Lastly, I oversized the front and back and will use a trim bit to match them to the assembled cabinet. A little sanding and they are ready for veneer.

I have a rant and its not a new one; I have a nasty reaction to MDF dust. I now wear a respirator when working with the stuff. I look pretty odd with a respirator, shooting muffs and safety glasses on but its all necessary to stay healthy!

[JonMarsh]

MDF is like peanuts, I think- some people have VERY consistent high intensity reactions to it; others, (like myself) don't, but that doesn't mean it isn't bad- a good minimal particulate mask is highly desirable regardless of whether you have a strong apparent reaction or not- it's not like the stuff is health food or anything, you know...

Something like this 3M 6000 mask is a good way to go if you don't want to spend much money and full masks make you claustrophobic...

https://www.amazon.com/3M-6200-6000-Facepiece-Respirator/dp/B001QF9C5C/ref=wl_it_dp?ie=UTF8&coliid=I20AMJ8LCP37V6&colid=2ZIYJOOR18KE3

Rabbet joints are a great way to go, first used them in the 70's, and the new project is using them- just got in a new Whiteside bit yesterday to finish up the panels for that project. OTOH, being square is not the exact nature of my problem.... :W

[orbifold]

er-ah, was this what you were talking about?

Images not available

The fasteners a SO CHEAP. Haven't had a chance to use, yet--must get cutting!

The simple way (referring to the original question) is to stack scrap pieces together with a piece cut with your setup dimension: ||=====|| like that. The equal signs stand for the flat piece and the || is the scraps to "measure" the thickness.
Then stick a rule on the total and read it. :B Too easy, right? This can be used whether you use the butt joint, rabbit, or whatever by running a scrap thru setup before making a throw away piece that costs you square footage and nerve endings.

[ThomasW]

er-ah, was this what you were talking about?

Jon doesn't own a brad nailer

[orbifold]

Thomas, that one is actually a pinner. Leaves a hole is almost too small to see. But, like I said, it is still i the box. I have yet to see it it'll poke thru the tight mdf surface. It should, and could stop the lateral slippage with glue till it sets.

[Dennis H]

Yeah, pin nailers rock! My Senco shoots 23 ga. (0.0226") pins with no head and the hole is nearly invisible.

[DeathMonk]

Crisis averted: