Im at the sanding stage of making my cabinets. All is cut. Im experiencing some difficulty along the 18mm edges of the MDF.
I find that Im not sanding it flat, but rather depending on direction, the uneven pressure from my hand is causing a 'hump' in the middle.
I realise this is basic woodworking skills, but I severlely lack. I have the sandpaper wrapped around a block of wood that I use to rub up and down the edge Im sanding.
Tips?
GeniX
If you are sanding an edge there are two problems you can experience.
One is as you have found, uneven pressure can easily result in humps and hollows on you edge.
The other common problem is the sanding block is not held exactly square to the wood and along the sanded edge you have some parts that lean one way, some lean the other way and some are square.
When you look down the edge any out of squareness becomes easily noticable.
The way to cure this in a simple manner is to locate a long sturdy piece of wood that is straight and about a foor longer than your edge. Gauged 4 x 2 is good for this but check it is straight first. Then buy your sandpaper in a roll as long as the board, glue the sandpaper onto the board so you now have a long sanding block. As long as your long sanding block is stiff and not bending you can easily get straight edges.
The other problem of sanding the edge square can be done by screwing a long flat board or several smaller guide blocks onto your sanding block so it is at right angles to your "long sanding block" and you can glide the squaring board along the face of the MDF.. I do this often and glue a sheet of felt on the "squaring baord so it does not mark the wood.
Now you can sand the edge straight and square quite easily.
Often cut boards are not exactly the right dimension. They can be wider at one end than the other. This is easily corrected by the long sanding block by a little more pressue at one end of the sanding stroke than at the beginning. For example.
It is also most helpful if you can arrange to clamp your MDF steady while sanding so you can guide the sanding block with both hands rather than trying to sand with one hand and hold the wood with the other.
If you are sanding an edge there are two problems you can experience.
One is as you have found, uneven pressure can easily result in humps and hollows on you edge.
The other common problem is the sanding block is not held exactly square to the wood and along the sanded edge you have some parts that lean one way, some lean the other way and some are square.
When you look down the edge any out of squareness becomes easily noticable.
The way to cure this in a simple manner is to locate a long sturdy piece of wood that is straight and about a foor longer than your edge. Gauged 4 x 2 is good for this but check it is straight first. Then buy your sandpaper in a roll as long as the board, glue the sandpaper onto the board so you now have a long sanding block. As long as your long sanding block is stiff and not bending you can easily get straight edges.
The other problem of sanding the edge square can be done by screwing a long flat board or several smaller guide blocks onto your sanding block so it is at right angles to your "long sanding block" and you can glide the squaring board along the face of the MDF.. I do this often and glue a sheet of felt on the "squaring baord so it does not mark the wood.
Now you can sand the edge straight and square quite easily.
Often cut boards are not exactly the right dimension. They can be wider at one end than the other. This is easily corrected by the long sanding block by a little more pressue at one end of the sanding stroke than at the beginning. For example.
It is also most helpful if you can arrange to clamp your MDF steady while sanding so you can guide the sanding block with both hands rather than trying to sand with one hand and hold the wood with the other.
GeniX
If you have access to a router I would suggest using a trimming bit to even out your edges. This is a bit that has a bottom mounted bearing exactly the same diameter as the cutter.
If you set the depth of cut so that the bit runs along the board you are joining to, and you run the base of the router of the surface of the board with the offending edge the you will get smooth accurate 90 degree cuts, that ,if you use a sharp bit, will need only finish sanding.
If you don't have a router, buy one!
I think it is the most valuble tool a speaker builder can own, as with a bit of practise, just about any process needed in cabinet manufacture can be carried out with one.
Other than that, Remp's idea is a good one, or you could borrow or buy a small hand plane.
But with all new techniques, practise on some scrap first
If you have access to a router I would suggest using a trimming bit to even out your edges. This is a bit that has a bottom mounted bearing exactly the same diameter as the cutter.
If you set the depth of cut so that the bit runs along the board you are joining to, and you run the base of the router of the surface of the board with the offending edge the you will get smooth accurate 90 degree cuts, that ,if you use a sharp bit, will need only finish sanding.
If you don't have a router, buy one!
I think it is the most valuble tool a speaker builder can own, as with a bit of practise, just about any process needed in cabinet manufacture can be carried out with one.Other than that, Remp's idea is a good one, or you could borrow or buy a small hand plane.
But with all new techniques, practise on some scrap first
Check Brian's comments about routing bits here: http://www.diyaudio.com/forums/showthread.php?s=&threadid=5715&perpage=15&pagenumber=3
If you work with wood more often than occasionally a router is a must.
If you work with wood more often than occasionally a router is a must.
You guys are going overboard here... All he really needs is what's called a shooting board... Its more commonly used with hand planes, but will work quite well with sanding as well. I thought that's what remp was going for, until I realized he was just making a HUGE sanding block! A shooting board is just a board clamped to the edge of the board to be sanded or planed and is used to give some extra support on the one side so that you'll be shooting straight down the edge. In other words, take remp's idea of a long straight board, clamp it to the edge you're sanding at the height you're sanding to. Then take your sanding block and sand until you're holding it flat on both surfaces.
Now, granted the routing trick is quicker and easier, but this way is cheaper, less noisy, and it helps you get some exercise in the process!!
Now, granted the routing trick is quicker and easier, but this way is cheaper, less noisy, and it helps you get some exercise in the process!!
GeniX
The edges you are talking about, if they are the edges you are going to glue together, then you shouldn't be sanding these. I made the same mistake on some cabinets I was making, a cabinet maker friend of mine told me to just glue the joint together, be they cut on a table saw, jointed, whatever. This will give you a better joint and avoid the problems just mentioned.
Bob2
The edges you are talking about, if they are the edges you are going to glue together, then you shouldn't be sanding these. I made the same mistake on some cabinets I was making, a cabinet maker friend of mine told me to just glue the joint together, be they cut on a table saw, jointed, whatever. This will give you a better joint and avoid the problems just mentioned.
Bob2
Well - my cuts are not perfect. Jig-saw doesnt give perfect enough that I can just make the cabinet straight. There is a little excess which needs to be taken off.
I have run into the issue of the 'hump' as I mentioned with sanding by hand. A friend reckons I should use a plane (which he apparently has, so I might pop around to his place to do it).
Other than that, if I understand right, Im making an L-shape from wood with sand paper on the bottom of the L, and than the upright of the L will serve as a guide to help against uneven sanding?
Im not too clear on Schaef's description of a shooting board - can someone clarify?
Don't have pictures, but I did a search on google for woodworking and shooting board. Here's some web pages that might be usefull:
http://www.millard.demon.co.uk/planingpoints/shootingboards/shootingindex.htm
http://nitwit.com/nws/article_1/article1.html
These should give you some ideas on how to accomplish what you want. If not, I can try some other things as well...
http://www.millard.demon.co.uk/planingpoints/shootingboards/shootingindex.htm
http://nitwit.com/nws/article_1/article1.html
These should give you some ideas on how to accomplish what you want. If not, I can try some other things as well...
Thanks Schaef - both links have been very useful! Descriptive enough to show how to make a shooting board, and the Fine Woodworking link even gives tips on doing the actual cut so far as position, holding and pressure are concerned!
Ill have to pop around to use my buddy's plane this weekend.
Bob2 - that would work well.. but planing may well prove easier as the amount I have to sand off each side does vary some.
Good links Schaef...
Bob's idea is a good one tho, if you cut and finish all your identical panels together ( use double sided tape to fix them), then even if they end up a little off, they will all be the same, this makes construction a little more even.
Genix- when cutting the mdf with a jigsaw, did you use a fence or guide block?. Both these techniques will help, as will the use of a new sharp blade.
Don't be tempted to force the tool when cutting, this will cause the blade to wander, especially in the vertical plane, resulting in non square cuts.
If you are just sanding off the roughness of the cut, however, rather than making the panels square and true, don't worry about it! Just use a good gap filling adhesive, such as construction adhesive or Gorrila glue, and the end result will be fine.
Bob's idea is a good one tho, if you cut and finish all your identical panels together ( use double sided tape to fix them), then even if they end up a little off, they will all be the same, this makes construction a little more even.
Genix- when cutting the mdf with a jigsaw, did you use a fence or guide block?. Both these techniques will help, as will the use of a new sharp blade.
Don't be tempted to force the tool when cutting, this will cause the blade to wander, especially in the vertical plane, resulting in non square cuts.
If you are just sanding off the roughness of the cut, however, rather than making the panels square and true, don't worry about it!
Just use a good gap filling adhesive, such as construction adhesive or Gorrila glue, and the end result will be fine.Thanks, pink!
I didnt use a fence or guide block while using the jigsaw. I didnt force it either. I dont know if my cut is at right angles to the adjacent sides - I think its fairly accurate as the jigsaw I used has a little platform around the blade which rests on the wood.
It was handheld
I might try the idea with sanding using an L-shape to try keep things 90 degrees, flat, and a lot more even.
GeniX said:
Thanks, pink!
I didnt use a fence or guide block while using the jigsaw. I didnt force it either. I dont know if my cut is at right angles to the adjacent sides - I think its fairly accurate as the jigsaw I used has a little platform around the blade which rests on the wood.
It was handheld
I might try the idea with sanding using an L-shape to try keep things 90 degrees, flat, and a lot more even.
First, next time you cut, use a straight edge, it'll help a lot! Now before you worry about that, a straight edge can simply be a piecec of plywood longer than the edge you want to cut that you know has been cut straight. (Stock 2x4's also work, but the rounded edges could allow for the base to wander under)
As to the streight cut, pinkmouse wasn't refering to holding the saw itself flat, (that was assumed) but that the blade will wander out of square vertically. To see what he means, hold your saw upside down (unplugged of course) and wiggle it left and right when looking straight at the cutting edge. This is one of the biggest problems with jigsaws! They're great for cutting curves, but lousy for straight cuts.
If you plan to do a lot more with speakers, I would recommend you get a decent circular saw and a metal straight edge with some clamps. You'll save yourself a lot of headaches!
And before anyone jumps in about table saws, yes they're better, but a circular saw (a good one as well) can be had for under $150 (US)! If you're interested GeniX, I can recommend some good saws for you. (I love my Porter Cable, and it was about $120, I believe!)
Hope things work out for you!
Thanks again - I've done my sanding.
I found that clamping a block over the sandpaper (with workbench under the sandpaper) and then sliding the edge I want to sand up and down along the block's edge keeps my edge reasonably good.
Not perfect ofcourse - but much better than when I was holding the sanding block in my hand and running it over an edge (which produced the hump mentioned many posts ago).
Any misalignements now will have to be filled in with wood filler. There shouldnt be any large gaps from what I can work out.
--
As for the saws - I do plan on doing more DIY stuff, but not for a wee while. This project was stretching things when I initially started, and I have spent more than I planned.
When I next start another project (possibly early next year), Ill look to buy a couple more tools. Feel free to recommend some.
Noting that I posess *no* cutting tools, I'd probably start with whichever are most important and slowly work my way down the list.
GeniX said:
Glad to hear you figured something out that works for you! Now you'll know how to do it more quickly next time, or maybe won't even have to do it next time! An alternative to wood filler, on the inside at least, would be to use caulking. I think it'll be cheaper and easier to apply. Remember, the only person seeing the inside is you, save the money for the visible portions of the project!
Now wait a minute, you said you used a jig saw, what happened to it? Its one of the three items I'd recommend for a basic set of tools for speaker building! Here's my list of what I'd recommend you look for:
1) a jig saw - at least here in the states you can get these for about $20 on the cheap end. (The more expensive ones do seem to cut better, but I haven't quite figured out why yet)
2) a circular saw - this, along with a straight edge, should make the sanding you had to do pretty much un-necessary.
3) a router - This is more of a later purchase that makes dadoes much easier to do. It also allows you to do some more sophisticated joints.
4) a table saw - this is for when you really are getting serious, this is a big ticket item!
5) a drill press - it sure makes drilling some holes a lot easier!
After these, you start getting into different sanders, scrapers, and other fun woodworking stuff, but with the first three, you should be able to build quite a few very nice speakers!
As for name brands on the first three, the "good" brands include Porter Cable, Makita, Panasonic, DeWalt, Bosch, Hitachi, and some others that I can't think of right now. Personally, I love my Porter Cable circular saw, it has a flat, rigid machined aluminum base, no safety buttons, and relatively light. My only complaint is there isn't a dust collection bag for it. (A dust chute, that shoots the dust everywhere, but no bag attachment for it)
What I'd do if I were you, would be to save up some money and buy one tool every couple of months, so you're not breaking the bank in one shot. The router will probably be the most expensive at between $150 and $200 USD for a good one that'll do what you need.
Okay, I've rambled enough...
You only really need a couple of tools
1) small Skilsaw type saw, you don't need a big one as you will only be cutting sheet material
2) Decent router
With these two tools and a decent straightedge clamp, you can build any speaker cabinet you can think of, and with any extra money just buy more bits and jigs for your router
Schaef's brand recomendations are all good, but as always with tools, buy the very best you can afford, they are much more reliable, accurate, and easier to set up!
1) small Skilsaw type saw, you don't need a big one as you will only be cutting sheet material
2) Decent router
With these two tools and a decent straightedge clamp, you can build any speaker cabinet you can think of, and with any extra money just buy more bits and jigs for your router
Schaef's brand recomendations are all good, but as always with tools, buy the very best you can afford, they are much more reliable, accurate, and easier to set up!
Schaef: Yeah I have jig-saw and cirular saw which are not mine - they will be going back to the kind friend who lent them in a while.
Of the brands you mention, at minimum DeWalt and Bosch are available.
PinkMouse: I have no idea what a Skilsaw type saw is - Ill do an internet search for it. Also I hear a router is highly recommended, but when I think router, I can only think of one thing (and thus one use) which is making edges into fancier shapes.
It will be interesting learning all the things it can be used for.
Thanks again guys - you're great help to 'noobs' like me :-D
Hey GeniX
Skilsaw = circular saw. It's actually a brand name that has come to mean the saw itself (like a hoover (UK), or a kleenex (US))
Routers can be used for the already mentioned edge-forming, and also to cut out the speaker holes with a circle jig, and then to let in the speakers so they lay flush in the cabinet. I cut my first speaker holes with a jigsaw, and they were nowhere near round!
Cheers, Dan
Skilsaw = circular saw. It's actually a brand name that has come to mean the saw itself (like a hoover (UK), or a kleenex (US))
Routers can be used for the already mentioned edge-forming, and also to cut out the speaker holes with a circle jig, and then to let in the speakers so they lay flush in the cabinet. I cut my first speaker holes with a jigsaw, and they were nowhere near round!
Cheers, Dan
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