router Help

[pjoseph]

I am building a sub for my room and wondering if you router the edges before or after you build the box.

Also if I am using .75" I would place my screws in the center which would be about .37" from the edge, now if the edges are rounded by a router will i have to place my screws in greater then .37"

I am in the planning stages making the plans since I am having the wood cut by someone else since I dont have a saw and not sure how much the router will take off, do i need to make the edges a little bit longer to compensate for what the router takes off.



Thanks

 

[Haoleb]

router the edges after the box is built. Before you do the roundover (im assuming thats what you want to do) get whats called a flush trim bit and run it along all joints to ensure that everything is squared up and flush. This will trim off any overhanging joints. Then go by with the roundover bit.

You generally want to run the router against the tool rotation as well. They spin clock wise so if the router is between you and the peice your doing you would go from left to right. You'll be able to feel the difference.

If your going to use screws with 3/4 material then either recess them a good bit or your probably going to hit them with the router. When I built my subwoofer box for my truck i used screws everywhere because I didnt want to wait for each joint to dry before i could do the next one so when i went to router it i routered nearly all of the screws in the process. I didnt care about ruining the bit but I dont reccomend it. Sparks fly everywhere and you'll trash the router bit.

Also, screwing into MDF isint the greatest option if you use MDF because it will likely bubble out where your screws are if you dont pre drill everything first. many people dont even use screws.

I'm not sure what you meant about making the edges longer for what the router takes off... Like i said earlier if you use the flush trim bit then making the panels a little oversized will ensure nice straight edges but it would mean you have to take more care in marking out where everything goes instead of just gluing stuff flush.

 

[pjoseph]

Thanks for your help.

 

[Warpdrv]

Another good product to use is 3/4" 13ply birch plywood....


If you can find it in your area... Its lighters then MDF, but more expensive.

 

[GTHill]

You can use screws with MDF if you predrill it. I don't recommend using screws, but other options are very expensive.

I route many of my panels before assembly, but most of those are on the inside.

One of the misconceptions of this thread is that a router cuts in 1/2 the thickness. This is something that you can control with using the correct router bits. If you pay attention while using the screws and countersink them a bit, the router bit won't hit the screws, not even close.

GT

 

[Swerd]

All the previous answers are good advice. Just the same, I would be very nervous routing an edge (roundover?) near where screws were used. A big bit like a ¾" roundover bit is hard enough to control with a hand-held router under normal conditions. It would be much more effective and safer if you use a table mounted router. Hitting a steel screw with a router bit should be avoided, it could be very dangerous.

I'm not sure how much material a ¾" roundover bit takes off, it depends on how deep you go. Before doing anything I would test things out on a piece of scrap wood. Put in several woodscrews a variety of distances from the edge of the scrap wood. Start at 0.37" from the edge and work your way in further away from the edge. Pre-drill the holes including a counter-sunk hole for the screw head, drive in the screws, and take them out. Then route the edge and see which holes are far enough away from the router bit.

For a subwoofer, a rounded over edge on the front baffle may be nice looking, but it serves no acoustic purpose like it would on a normal speaker. If you must use screws, maybe you should skip the rounded edge.

 

[GTHill]

All the previous answers are good advice. Just the same, I would be very nervous routing an edge (roundover?) near where screws were used. A big bit like a ¾" roundover bit is hard enough to control with a hand-held router under normal conditions. It would be much more effective and safer if you use a table mounted router. Hitting a steel screw with a router bit should be avoided, it could be very dangerous.

I'm not sure how much material a ¾" roundover bit takes off, it depends on how deep you go. Before doing anything I would test things out on a piece of scrap wood. Put in several woodscrews a variety of distances from the edge of the scrap wood. Start at 0.37" from the edge and work your way in further away from the edge. Pre-drill the holes including a counter-sunk hole for the screw head, drive in the screws, and take them out. Then route the edge and see which holes are far enough away from the router bit.

For a subwoofer, a rounded over edge on the front baffle may be nice looking, but it serves no acoustic purpose like it would on a normal speaker. If you must use screws, maybe you should skip the rounded edge.

What I'm saying is don't use such a big round over bit. Use a 3/8" bit. It will look nice and be much easier to use.

GT

 

[Swerd]

What I'm saying is don't use such a big round over bit. Use a 3/8" bit. It will look nice and be much easier to use.

Good idea, I agree with you.

You can always use screws and glue. The screws act as clamps while the glue sets. Afterwards, remove the screws, fill the holes, and then the router bit can't hit anything.

Good luck with your subwoofer .

 

[Haoleb]

Hitting a steel screw with a router bit should be avoided, it could be very dangerous.

As long as your using the OSHA approved squint technique you should be ok.

 

[mtrycrafts]

...

Also if I am using .75" I would place my screws in the center which would be about .37" from the edge, now if the edges are rounded by a router will i have to place my screws in greater then .37"...
Thanks

Why not use biscuit joinery? Will you veneer your box afterwards?

 

[GTHill]

Why not use biscuit joinery? Will you veneer your box afterwards?

Technically speaking, biscuits aren't really for strength, but for alignment. They do add some strength of course. The other downside is that there is a cost of tools involved. I personally use Festool Dominos, but it's a $1000 to get going with that tool. See my ever dragging on build to see some pictures.

GT

 

[mtrycrafts]

Technically speaking, biscuits aren't really for strength, but for alignment. They do add some strength of course. The other downside is that there is a cost of tools involved. I personally use Festool Dominos, but it's a $1000 to get going with that tool. See my ever dragging on build to see some pictures.

GT

You mean that shear strength of that glue joint is less than the screw's holding strength?
He could use less expensive joiners and he'd have it for many other projects

 

[highfigh]

I am building a sub for my room and wondering if you router the edges before or after you build the box.

Also if I am using .75" I would place my screws in the center which would be about .37" from the edge, now if the edges are rounded by a router will i have to place my screws in greater then .37"

I am in the planning stages making the plans since I am having the wood cut by someone else since I dont have a saw and not sure how much the router will take off, do i need to make the edges a little bit longer to compensate for what the router takes off.



Thanks

The edges should be flush and the other point about using a flush trim bit is a good one. Once the routing is done, sand anything that needs it. If you have bulges from screws, I have found that a relatively fine file works best and you'll have plenty of flat area to use as a guide.

There's no rule that says you have to use a 3/4" radius bit, either. If you definitely want to use that radius, you can always drill anad screw on a slight angle to keep the screw heads away from where the roundover will be. Any screw holes or countersinks can be filled with Bondo. It's about the most stable filler you'll find and it's similar in hardness to MDF. If you paint the boxes and don't want to see dry areas where the MDF edges are, you can brush a coat of Zinnser Sanding sealer shellac over them, let it dry (should dry in about 1/2 hour), sand it and pain with whatever you want. Autobody primer and paints work great for this kind of thing.

 

[Warpdrv]

Honestly many many people have glued boxes together without screws, there is really no need for screws, just get some inexpensive clamps and there is no worry about routing around screws......

There are plenty of places to get cheap wood clamps, they don't need to be extravagant, and will provide plenty of pressure needed for gluing a box together, and after you can easily use silcone to seal inside edges if you feel the seal is not up par....

IMO screws are not attractive and just add to more work to fill and clean up after them.

I certainly don't care for screws in MDF...... Ever... for Ply they are fine, but not very good with MDF.

 

[Haoleb]

If this is a one time thing you could probably even borrow or rent clamps.

I woudlnt reccomend getting the cheapest clamps you can find, even if you will only use them once or twice, if your going to buy something like that you'll only waste your money if you go really cheap.

 

[Warpdrv]

I always find the investment of tools to be one of the most rewarding investments, even if I don't use that tool again for a long time, I still have never felt that I was wasting my money on it. In fact I at times will try to find projects to do in order to make use of those tools...

Buy quality things that last.....

 

[highfigh]

Honestly many many people have glued boxes together without screws, there is really no need for screws, just get some inexpensive clamps and there is no worry about routing around screws......

There are plenty of places to get cheap wood clamps, they don't need to be extravagant, and will provide plenty of pressure needed for gluing a box together, and after you can easily use silcone to seal inside edges if you feel the seal is not up par....

IMO screws are not attractive and just add to more work to fill and clean up after them.

I certainly don't care for screws in MDF...... Ever... for Ply they are fine, but not very good with MDF.

The screws basically hold it together while the glue dries and a finish/brad nailer or box stapler works fine, too. I did car audio for years and we made literally hundreds of sub boxes with MDF, yellow wood glue with a Senco stapler (2", I think) and only one came apart, because the guy just couldn't wait and cranked it after we told him to not to. It's a good idea to seal the edges, anyway. MDF is basically a paper product, in that it pulls apart in layers when the screws are going through the thickness and when they're in the edge, it's too easy to split it. Cabinet screws are available and used by cabinet shops because they have much coarser thread. Most big box stores have them with the drywall screws. However, as mentioned, they do make more work and are definitely not attractive. Trim head screws are less likely to spread the particles and since they're smaller, are easier to fill.

For clamps, Harbor Freight is about the cheapest and it doesn't need a tremendous amount of pressure- too much means the glue squeezes out and causes a weaker joint.

 

[highfigh]

If this is a one time thing you could probably even borrow or rent clamps.

I woudlnt reccomend getting the cheapest clamps you can find, even if you will only use them once or twice, if your going to buy something like that you'll only waste your money if you go really cheap.

Generally true. I bought some from Harbor Freight and they weren't made for quite as much as I used, which caused the pivot for the lever to shear off. I super glued them back in, drilled through the faces and used a #10-32 screw with a nylock nut/ Red Lok-Tite and it's definitely strong enough, now. It didn't shear on all of them but for the little time/effort/expense, I'll probably do it to the rest. Pony and Jorgenson clamps are very strong and the Pony use regular threaded pipe to determine the length. The ones in Warpdrive's photos look like Bessey, which are excellent, although pricey.