# Cutting slots in mdf



## Dado (May 13, 2012)

I need to (plunge) and cut 3.2mm slots in 3mm MDF!
I am using a hand held router and routing jig.
What type bit would you reccomend to get a clean cut top and bottom?

Thanks


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## Phil P (Jul 25, 2010)

Macsdado said:


> What type bit would you reccomend to get a clean cut top and bottom?


Hi Mac(?) and welcome to the forums!

A good sharp straight cutter should work fine on MDF. You could go to the expense of a down shear spiral, but personally I think that's overkill. If possible hook up a vacuum cleaner to the router. To help keep the cut clean because such a small cutter is more likely to choke on the cutting swarf (waste). It there is a bit of feathering at the edges of the cut this can always be removed by a light pass with a bit of P120 grit sanding paper

Regards

Phil


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## Dado (May 13, 2012)

*lots of slots*

Thanks Phil
I have tons of slots to cut so I intend on geting a good cutter!
I have vacuum.
I was thinking upcutter to avoide burn on the plunge? but I have not tried this yet.
but also a down cutter with a slow manual plunge, also spiral for the cut?

How could alittle slot be so tricky?

Dado


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## jschaben (Jun 21, 2009)

Macsdado said:


> Thanks Phil
> I have tons of slots to cut so I intend on geting a good cutter!
> I have vacuum.
> I was thinking upcutter to avoide burn on the plunge? but I have not tried this yet.
> ...


The material is only 3mm thick, shoudn't be to bad. My weapon of choice would be an upcut spiral.


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## Phil P (Jul 25, 2010)

Macsdado said:


> I was thinking upcutter to avoide burn on the plunge? but I have not tried this yet.


I think that scoching MDF is mainly down to not removing the waste material fast enough and not feeding quickly enough. Single flute cutters actually remove waste with less scorching than 2-flute cutters and suffer less from scorching (because they have massive gullets in comparison) and were the preference in manufacturing industry on pin and manual routers from the thirties until the advent of CNC routers in the late 1980s. I'm not a big fan of spirals on manual routing - they are ridiculously expensive for a start and I'd say that nine times out of ten they are unnecessary if the correct routing technique is used (which puts me at odds with about 50% of the folk on this forum, I guess :fie - I've been informed that they came about because of the need to remove more material on the higher speed CNCs which started to appear in the early 90s when cutting feed rates went up from 3 to 4 metres/minute to over 10 metres/min, a bit faster than you'll ever get with a hand router, and if fed too slowly especially without adequate extraction spirals can overheat and burn out as well as scorch timber. One thing I wouldn't do is plunge too slowly - that will possibly cause scorching, a common fault with beginners

Having now tilted at a few windmills I'll wish you good luck!

Regards

Phil


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## harrysin (Jan 15, 2007)

Phil. is quite obviously talking from experience Mac.


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## Dado (May 13, 2012)

Just tried a single straight bit and it is perfect. A little bit of tear top and bottom but a rub of paper removes it.

Thanks.


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