# How to fit ant-slip discs into hardwood floor



## jjay66 (Oct 6, 2009)

Hi

Need some help with this one!

I need to fit 250+ anti-slip discs into a pre-finished and pre-laid hardwood floor. The discs are 8mm (1/3") deep and need to be fitted in the middle of the 180mm (6") board at 70mm (3") centres.
The floor is Ironwood which is approximately 4 x harder than Teak and about as hard as wood gets and something I haven't worked with before.
There is no margin for error. I was hoping someone might be able to comment on the pros and cons of the following approaches to getting this job done:

1. 50mm Forstner bit. I'm thinking you'd probably need a fairly heavy duty router for this. Since I cannot clamp to the floor I was considering a Festool router? I have the guide rails as I use a Festool Saw and thought that might offer a stable and consistent base. Failing that what about attaching a larger piece of ply to the router base which I could stand on to ensure no movement. The obvious advantage of the Forstner is accurate centring to a drilled guide but will this big a bit stuggle with the density of the flooring?
How many Forstner bits am I likely I go through on this job?

2. Creating a 50mm hole jig and routing out the holes with a 1/2" router cutter. Smaller cutting area should be easier but how do I fix the jig to a pre-finished floor bearing in mind I will need to repeatedly move it. Also foresee problems locating accurate centres.

Any input gratefully received.


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## jjay66 (Oct 6, 2009)

Further concern is the speed of the router v. maximum recomended speed for Forstner in hardwood. Anyone reccomend any good drill guides?


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## rstermer (Apr 22, 2008)

jjay66 said:


> Hi
> 
> Need some help with this one!
> 
> ...


I am certainly no expert, but I think putting a forstner bit in a router is taking quite a risk. I think forstner bits are designed to run quite slow, 250- 500 rpm or so and the minimum speed you are going to be able to run a variable speed router is maybe 8000 rpm, that's about 16-32 times faster than the bit is designed to run. It doesn't sound safe to me.

If the floor is pretty flat and smooth you might try a vacuum clamping system to hold your jig in place. Perhaps you could incorporate an extension to pick up a couple of the holes from the prior row to keep you properly indexed.

I've had a little experience with ironwood and I think bit life may be a problem for you, it is tough stuff. In head to head tests Whiteside bits seem to always come out on top (longest life, smoothest cut), but they are expensive.

I'd get some scrap wood and try out a few different approaches before I applied my router to the actual floor, any mistake could be expensive.

Good luck,
rstermer


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## bobj3 (Jan 17, 2006)

Use the router inlay way,,the disk will snap right in place..and stay in place...

Router Workshop: reverse inlay

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jjay66 said:


> Hi
> 
> Need some help with this one!
> 
> ...


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## rstermer (Apr 22, 2008)

I did a little research online on the safety of using a forstner bit in a router and found the following:

http://www.ridgidforum.com/forum/showthread.php?t=20852

Bottom line: *NOT SAFE!!!!!!!!!!!*

rstermer


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## BigJimAK (Mar 13, 2009)

+1 on BobJ's template. If its a large open area I'd build some kind of registration jig, even if it meant two long side-strips and a bunch 6"x3" blocks to use for horizontal registration. Even if it follows a winding path I'd find a way, even if it was printing out a bunch of large CAD drawings with registration marks and laying them out on the area.

Depending upon the layout and if the budget is there, a digital surveyors-type tool for marking centerpoints might be practical too.

I'd be guessing on the # of bits but 6-10 whiteside bits would get you started. You might need to overnight some more. It's unlikely to be 1 bit or 50. Between that number it can vary significantly according to the skill of the operator and what impurities are in the wood. If you burn a bit, even on the first disk, its time for another.


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## jjay66 (Oct 6, 2009)

Thanks for the responses guys. I did some research and quickly discounted the Forstner route too! Actually, although I love a challenge, I passed on the job. 

They were in a hurry and I was suspicious because it was a joinery company looking to get the job done. I guess they wanted to pass the responsibility for possibly wrecking the new floor in a restaurant (due to open in a week or so) onto someone else!
If I'd had the contract to lay the floor too I probably would have taken it on and done some experimenting with off cuts but no such luxury! Ideally the discs should have been inlaid in each board before it was laid. I'm thinking the architect had a brainwave at the last minute...

As it stood there were too many variables and, not enough time to experiment and I'm guessing not enough budget to cover the risks of damaging the flooring.
Thanks for the solutions though. I think I would have made a large jig with a set of as many holes as was practical cut into it to help with registration and stability, oh, and bought a shed full of bits!


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## BigJimAK (Mar 13, 2009)

jjay66 said:


> I think I would have made a large jig with a set of as many holes as was practical cut into it to help with registration and stability, oh, and bought a shed full of bits!


LOL.. Definitely not a job for HSS bits! <g>


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