counterbore/countersink vac motors ?

[77-1212596771]

Just a short question.

I saw flowbenches where the vac motors were just glued or screwd on the mdf plates. Only a small hole is bored for the air intake at the motor.

I want to use two thick MDF plates and had the idea of boring a small hole in the first plate and a 144mm hole in the second, where the vac motor fits into.

Would this be a prefered way to get a better isolation when using silicone and a more stabile fit of the motors ?

Could this harm the motor due to heat shielding ?

See following picture:

(The louvers would be still getter fresh air)

Cheers,

Daniel

[bruce]

This is exactly how I mounted my motors in my PTS Plans build. Not really a counter bore though as I cut the hole for the air inlet in one MDF panel and cut another hole in the second MDF panel to fit the motor. I used a large o-ring to seal the motor to the panel. You could get fancy if you wanted and actually router a groove for the seal to fit in.

[77-1212596771]

doh!

Do I really have overseen that in the plans ?

Bruce you have to put photos to the plans

So I am on the right way.


How have you done the 144mm cuts ? The usual hole-saws I have found are just up to 120mm.

Daniel

[bruce]

It's not called out in the plans specifically as I left that up to the individual on how they mount the motors.

Did you not see the pics of my build in the PTS plans area?

I used a router to cut the holes with a locating pin in the center, it was actually a German (?) power tool I purchased from Harbor Freight specifically for making holes in wood. I'll see what the name of it is when I get in the shop later. The tool cost me less than $20?



Edited By bruce on 1213725823

[77-1212596771]

[color=#000000]Do you mean following ?


or a router like following ?


The first thing is called "lochs

[bruce]

This is what I used:



It can be a scary tool if it grabs the work while cutting the holes! I used this tool for all my large holes, the smaller ones I used holes saws.

[77-1212596771]

Thats cool! I never seen such a tool before.

Thanks

[bruce]

Just a little construction advise; I used a scrap piece of MDF and drilled a 1/4" hole for a dowel pin to use as a locating pin, marked my hole location in the piece of MDF I was cutting and drilled a 1/4" hole. I then put my piece with the 1/4" hole over the pin. The pin only stuck up 1/4-3/8 of the way up this hole. I then used the FERM tool and cut my hole, the FERM tool uses the same 1/4" hole for it's pivot. I also drilled a start hole for the cutter on the outside diameter so I was not plunging the cutter into my MDF.

By doing this with the pin it keeps the scrap hole piece in place so it doesn't come free when you finish the cut and do "wild things" with your tool . . . again if this tool grabs and you are not holding it firmly it will take a ride! Now that little cutter can do some evil things to wood so you can imagine what it can do to flesh!

Yes I did have it take a ride once and only once . . . gained respect for it real fast after that!!!!!!!!

All of this might be obvious for everyone but, I am NOT a wood worker and wanted to point this out to other non-woodworkers so nobody gets hurt!

[77-1212596771]

Hey Bruce,

I got the hint for the german word for that machine. It's called: Rotationsschneider (rotation cutter). Most sold machine is the Bosch RotoCut , however It cost a bit (multiplicate with 7) more than your variant.

I will check out if I can find a machine, but I will also contact some local wood cabinet makers for an offer.

Thanks again,

Daniel

PS: I already thought about a little translation / tool guide. I think many other users from non-english countries will have similar issues sometimes.

[Moriniman]

How about a trepanning bit?

[77-1212596771]

Good point Paul,

I saw:


on ebay some days ago, but it looks so fragile. Is that really durable for lets say 20 or more holes ?

Daniel

[bruce]

I'm going to interject again . . . thinking back when I cut my holes I used a single blade bit like the one above to cut the holes I could fit in my drill press. I do not recall using the FERM tool to cut the holes in my motor panel support plate so more than likely I used the single blade cutter and the drill press. The boards that had holes located to far in the panel I cut with the FERM tool. This would have been the top hole and the side access holes if I recall correctly.

Sorry to many things on my mind right now besides flowbench projects.

[77-1212596771]

[Sir Yun]

those work well, but best in a drill press. i used one when i was building my ueber matrix braced speaker enclosures..(good for several hundred holes in not so tool friendly mdf). and i just touch the cutter up on a grinder very once in a while.

used it to cut alloy plate as well which works a treat.

you can buy a router for a little as 25 euro's.. not it won't last forever but due to the cost they will give you a new one on sight if it breaks (at least where i live). cheapest..