Router bit bearing grooves MDF template

[daviddoria]

I made a template out of 3/4" MDF to route some circles. After routing a handful or circles, I noticed that the bearing on the bit had kind of pushed a channel/groove into the inside of the hole in the template. This causes a little bit of a problem if I don't set the bit depth the same for multiple passes at different depths, because it then traces a slightly different circle and leaves a ridge inside the hole that is routed. Is there any better material than MDF to make a template like this from? Plywood wouldn't probably squish like the MDF did, but it has its own ridges that may or may not be a problem.

 

What do you guys usually use for router templates like this?

 

Thanks,

David

[wdwerker]

You can rub some glue into the edge of the MDF . Let it dry then sand lightly. This will stiffen and harden the MDF and make the edge wear better. Epoxy also works if it is a jig you will be using repeatedly .

[..Kev]

Epoxy would be my choice for durability..

[daviddoria]

Interesting, I'll give that a try. I also had trouble where by screwing and removing countersunk screws through the template into many workpieces the MDF actually "delaminates" - where it kind of tears through the thickness (that is, about a 3/8" "flap" peels off of the 3/4" template). Is that a common occurrence as well? Anyone use some kind of plastic for something like this? Or is there a High Density Fiber that can be obtained and is better than the Medium Density Fiber (MDF)?

[..Kev]

For jigs that I'm going to use multiple times, I'll use plywood or hard board so this type of stuff doesn't happen.

[Tom King]

I have some jigs I made 20 years ago out of Baltic Birch, with epoxy saturated working surfaces, which were sanded back to shape way back when I made them, that still work just fine.

[dwacker]

You should not have the grooving issue even with MDF. The problem is likely in your setup not the MDF.

[dwacker]

Bearings reduce friction. If the bearing or setup is not right causing the bearing to not work properly you will have friction. 

[daviddoria]

Mike Woodsap - I am definitely pushing quite hard. I am taking a 3/8" deep pass (is that too deep? Whiteside told me I should be fine with up to 1/2", but that seemed like too much). I am using about a 1" long cutter, so I can't take any less than that and still have the bearing hit the top of the 3/4" thick template. The hole has to be fairly deep, and I was unable to reach the bottom with a shorter bit, and I have to do a lot of these so changing bits mid-hole did not sound like fun. I have been told that I should use a bushing guide and a straight bit (without a bearing) to do something like this, exactly for the reason of not being able to select my depth of cut how I want, but rather being forced into it by geometry constraints. Does that seem like the right thing to do?

[dwacker]

What are you making? What Im getting is that you are template routing circles. If this is the case you should not be trimming more than 1/3 the bit diameter.

[daviddoria]

I am making beer flights - so there are 1 1/4" deep, 2" diameter holes for the small glasses. I am using a 1/2" diameter bit. That's interesting, so if I get a larger diameter but I can take deeper passes? It sounds like my 3/8" deep passes are more than 1/3 of my 1/2" bit diameter. It seems to work ok- what is the problem supposed to be?

[wdwerker]

You can get a 2" forstner bit for about $27 at Lowes. Do you have a drill press , or access to one ?

[dwacker]

Your plunge routing not template routing. If you can't use a drill to remove the bulk and want to use a router you have to keep the bearing spinning otherwise you are just trashing your bit, bearing and template. A upcut spiral and bushing will clean out the center leaving a small edge to come back and template rout with your pattern bit.

[Dan S]

For a beer flights, I'd just use a Forster bit, or maybe I'd chamfer the top of the holes with a router. Depending on the wood species, a quality Forster bit leaves a decent surface finish. You could also try this method.

 

I'm with Tom on the templates, baltic birch  makes a much better template, MDF is just to soft. In my opinion MDF should only be used with collars.

[dwacker]

MDF is plenty hard I have templates that are 10 years old and have made literally thousands of cabinet doors that are still in perfect condition. If your bearing damages the mdf your stopping the the bearing and destroying it, dust removal is the key.

[Dan S]

MDF is plenty hard I have templates that are 10 years old and have made literally thousands of cabinet doors that are still in perfect condition. If your bearing damages the mdf your stopping the the bearing and destroying it, dust removal is the key.

 

perhaps you have better MDF.

[dwacker]

perhaps you have better MDF.

 

Is there such thing as "better" MDF. If your messing up MDF templates your not doing it right.

[wdwerker]

I clean and give my router bearings a tiny squirt of bearing lube to keep them spinning freely. Some MDF is much softer. Glue or epoxy will stiffen it up and make it wear better. Baltic is better for long term use templates.

[Dan S]

Is there such thing as "better" MDF. 

 

O yea,

 

buy a sheet from Menards, Lowes, Home Depot, or some other supplier and start cutting them, you will see a difference. I've seen differences in color, weight. Some stuff yields fine dust when cut, others leave what feels almost like little grains of sand.

[dwacker]

O yea,

 

buy a sheet from Menards, Lowes, Home Depot, or some other supplier and start cutting them, you will see a difference. I've seen differences in color, weight. Some stuff yields fine dust when cut, others leave what feels almost like little grains of sand.

 

I was just being a wise ass, I just buy HD MDF for this sort of stuff, its cheap and not good for much else.

[Rvlewis]

I've had similar trouble with bearing grooves in MDF. Probably mostly technique I'll freely admit, but I do use an epoxy wood hardener to make the MDF templates more reliable.

For templates that I intend to use a lot or for applications that just require very high precision routing, I use pieces of clear polycarbonate (ex:Lexan). Polycarbonate machines really nicely, unlike acrylic (ex:Plexiglas), which tends to chip and is really rough on your tooling.

I like to use 1/2" poly, but you can't find that thickness at Home Depot. I normally go to a local industrial plastics company and buy their remnants. Polycarbonate is more expensive than acrylic, but in my opinion the cost is largely offset by being pretty gentle on expensive bits.

[Alan Bienlein]

Try applying some super glue to the edge of the mdf template and spray with some accelerator if you have it. This will harden the edge and make it more durable. This is what I do to all my mdf templates.