RogerS
Established Member
Inspired by DaveL's dust filter I've been meaning to build one myself and finally it made it up the TUIT list.
Like DaveL I'm using the Axminster fine dust filter and coarse filter.
and my fan is this one
It moves about 2000 m3/hour which should be large enough for my workshop.
Scanning the offcut pile I found some 19mm ply for the sides. Didn't have enough for the two ends so found some old carcassing. It's going to be a long beast (about 3ft) as I want to make sure that the filter can expand down its' full length and the fan is also quite long. Maybe ply is a bit OTT but it's there to be used.
Design criteria are the ability to replace the two filters relatively easily and also to be able to remove the fan if need be. Nothing rocket science so far. A fingerguard would be good as well.
Sides cut and the two ends marked up.
Now how to cut a nice circle and a square?
Circle first. The quick and dirty solution would be the jigsaw but I felt I wanted a proper circle. No trammel to attach a router to but thinking upside down, there's the router table which is built around a Festool MFT. (The original idea of combining the two was to be able to quickly remove the Incra fence when I wanted to use it as an MFT. That was three years ago and the Incra fence has never been removed!). But the one advantage is that you don't worry too much about screwing things into the top.
So I drilled a hole in the ply to match the router cutter
and screw a pivot through the centre of the ply.
The Incra fence has been pushed back as far as it will go as I really didn't want to unbolt it.
As you can see, the idea being to gradually wind up the cutter and rotate the ply so creating a circular cut. Just have to remember when the cutter breaks through not to have the fingers in the way.
It worked although for one hairy moment, I'd let go of the ply to get underneath to raise the cutter a bit more and was too lazy to turn the router off. The rotating cutter acted on the ply like a miniature gearwheel and promptly set the ply spinning with the high possibility of the fixing screw coming undone. My very own 'flying saucer'.
Taking things a bit more steadily, produced the hole
To be honest, I have to ask myself was it worth it as the quality of the shuttering ply left the cut line pretty manky.
Now for the square hole. I'd remembered that I wanted some mechanism to hold the filters in place but something that would be easy to undo when the time came. I thought about it a lot and over-engineered as usual..thinking about homemade camlocks etc. In the end, I came to the conclusion that a second ply rectangle cut slightly undersized and located using threaded rod was about as simple and foolproof as it got.
Still got to cut those neat squares tho'. I cut one side with the jigsaw and thought that it lacked finesse. I then remembered that I'd bought a Trend Varijig for another project but that it had gone unused and unwrapped to this day.
The Trend Varijg. Allows you to cut square or rectangular holes using a router and guide bush. Took me ages, it seemed, to work out how it assemble it. Then I was faced with the problem of how to clamp it down especially when there wasn't going to be much meat left around the periphery of the ply. Trend do sell clamps for this purpose but in my case even they wouldn't work.
MFT to the rescue. The MFT comes with clamps that fit through the holes in the top of the MFT.
That worked for one end of the Varijig but, still resolutely refusing to remove the Incra fence, there were no convenient holes to clamp the front and so I resorted to a normal clamp and fixed the front of the Varijig to the MFT frame.
All the time I'm saying to myself, you'd have had this done by now if you'd use the jigsaw.
So started cutting and the first light cut fouled the Incra fence and so bowing to the inevitable I unbolted it.
Why didn't I use a jigsaw?
Made the next pass only to realise too late that the ply had slipped underneath the Varijig.
Not that impressed with the Varijig by this time. Nice idea but using it in earnest leaves a lot of unanswered questions re workpiece clamping. It also begs the question about the whole idea of the Varijig. Great if you're going to use it day in/day out but in reality, it's a bugger to store assembled..long arms jutting out everywhere and so the only sensible solution is to undo it all and put it back in the box until the next time.
Back to the box. Two square holes cut later and still thinking about that jigsaw, I started gluing and pocket-holing.
Tapped the ply for the threaded rod but Araldited them in place just for the hell of it. Installed the filter and by pure chance stuffed my hand down inside each sock to tease it down inside the box only to discover that each pocket is prevented from opening and doing its' job because there are two threads per pocket keeping them closed. Useful to know that.
Crimped up the cable ends nicely as I didn't want the cables coming loose over time. Besides it's the proper way to do these things.
And fitted the fan.
That's it.
Still thinking about the fingerguard.
Like DaveL I'm using the Axminster fine dust filter and coarse filter.
and my fan is this one
It moves about 2000 m3/hour which should be large enough for my workshop.
Scanning the offcut pile I found some 19mm ply for the sides. Didn't have enough for the two ends so found some old carcassing. It's going to be a long beast (about 3ft) as I want to make sure that the filter can expand down its' full length and the fan is also quite long. Maybe ply is a bit OTT but it's there to be used.
Design criteria are the ability to replace the two filters relatively easily and also to be able to remove the fan if need be. Nothing rocket science so far. A fingerguard would be good as well.
Sides cut and the two ends marked up.
Now how to cut a nice circle and a square?
Circle first. The quick and dirty solution would be the jigsaw but I felt I wanted a proper circle. No trammel to attach a router to but thinking upside down, there's the router table which is built around a Festool MFT. (The original idea of combining the two was to be able to quickly remove the Incra fence when I wanted to use it as an MFT. That was three years ago and the Incra fence has never been removed!). But the one advantage is that you don't worry too much about screwing things into the top.
So I drilled a hole in the ply to match the router cutter
and screw a pivot through the centre of the ply.
The Incra fence has been pushed back as far as it will go as I really didn't want to unbolt it.
As you can see, the idea being to gradually wind up the cutter and rotate the ply so creating a circular cut. Just have to remember when the cutter breaks through not to have the fingers in the way.
It worked although for one hairy moment, I'd let go of the ply to get underneath to raise the cutter a bit more and was too lazy to turn the router off. The rotating cutter acted on the ply like a miniature gearwheel and promptly set the ply spinning with the high possibility of the fixing screw coming undone. My very own 'flying saucer'.
Taking things a bit more steadily, produced the hole
To be honest, I have to ask myself was it worth it as the quality of the shuttering ply left the cut line pretty manky.
Now for the square hole. I'd remembered that I wanted some mechanism to hold the filters in place but something that would be easy to undo when the time came. I thought about it a lot and over-engineered as usual..thinking about homemade camlocks etc. In the end, I came to the conclusion that a second ply rectangle cut slightly undersized and located using threaded rod was about as simple and foolproof as it got.
Still got to cut those neat squares tho'. I cut one side with the jigsaw and thought that it lacked finesse. I then remembered that I'd bought a Trend Varijig for another project but that it had gone unused and unwrapped to this day.
The Trend Varijg. Allows you to cut square or rectangular holes using a router and guide bush. Took me ages, it seemed, to work out how it assemble it. Then I was faced with the problem of how to clamp it down especially when there wasn't going to be much meat left around the periphery of the ply. Trend do sell clamps for this purpose but in my case even they wouldn't work.
MFT to the rescue. The MFT comes with clamps that fit through the holes in the top of the MFT.
That worked for one end of the Varijig but, still resolutely refusing to remove the Incra fence, there were no convenient holes to clamp the front and so I resorted to a normal clamp and fixed the front of the Varijig to the MFT frame.
All the time I'm saying to myself, you'd have had this done by now if you'd use the jigsaw.
So started cutting and the first light cut fouled the Incra fence and so bowing to the inevitable I unbolted it.
Why didn't I use a jigsaw?Made the next pass only to realise too late that the ply had slipped underneath the Varijig.
Not that impressed with the Varijig by this time. Nice idea but using it in earnest leaves a lot of unanswered questions re workpiece clamping. It also begs the question about the whole idea of the Varijig. Great if you're going to use it day in/day out but in reality, it's a bugger to store assembled..long arms jutting out everywhere and so the only sensible solution is to undo it all and put it back in the box until the next time.
Back to the box. Two square holes cut later and still thinking about that jigsaw, I started gluing and pocket-holing.
Tapped the ply for the threaded rod but Araldited them in place just for the hell of it. Installed the filter and by pure chance stuffed my hand down inside each sock to tease it down inside the box only to discover that each pocket is prevented from opening and doing its' job because there are two threads per pocket keeping them closed. Useful to know that.
Crimped up the cable ends nicely as I didn't want the cables coming loose over time. Besides it's the proper way to do these things.
And fitted the fan.
That's it.
Still thinking about the fingerguard.
