With that thickness I would definitely avoid the jigsaw. Plan it right and you can do the recess then the cutout. Just go round in steps of 10mm or so. Just have to be careful on the last bit where there is only a thin bit holding on the edge. I try to push into the middle there to leave a small proud bit that can be filed down.
As the baffle is so thick I would also use a 45 degree chamfer on the inside edge to give the driver better breathing.
As the baffle is so thick I would also use a 45 degree chamfer on the inside edge to give the driver better breathing.
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Yes, a simple purpose made compass circle cutting jig will work. 38mm is a lot of MDF - as richie says, unless you have something like a Porter Cable 7500 series 3HP production router - those 14lbs of mass really help reduce vibration and chatter
I think you wanna go slow and make several passes with a 1/2" diameter plunge bit. The up-cutting spiral bits tend to run faster and clean chips out of your way, but the straight flute bits are much cheaper.
WEAR DUST MASK AND EYE PROTECTION - MDF dust goes everywhere (even into your shorts, I've found ) and is no fun at all.
I think you wanna go slow and make several passes with a 1/2" diameter plunge bit. The up-cutting spiral bits tend to run faster and clean chips out of your way, but the straight flute bits are much cheaper.
WEAR DUST MASK AND EYE PROTECTION - MDF dust goes everywhere (even into your shorts, I've found ) and is no fun at all.
Yes, the router is definitely the tool I'd choose for this task.
All of the previous responses gave good advice. It's probably worth your effort to review previous threads where this general topic was discussed:
http://www.diyaudio.com/forums/equi...le-jig-limited-compatibility.html#post4344730
http://www.diyaudio.com/forums/construction-tips/271242-custom-circle-jig-dewalt-compact-router.html
http://www.diyaudio.com/forums/multi-way/257120-open-baffle-3-way-speakers.html#post3946862
http://www.diyaudio.com/forums/construction-tips/247290-cutting-circles-jig-saw-2.html#post3929167
The recess (or shelf) can be cut after the main cutout. Use a bearing-piloted bit, with the bearing guided along the edge of the main cutout. The bearing RADIUS should be smaller than the bit's cutting RADIUS by the desired width of the shelf. However, I probably wouldn't use this method.
Instead, I'd make an initial pass with the circle jig's outside cutting diameter adjusted to the large diameter of the recess, and the bit depth adjusted to the depth of the recess. Then, decrease the jig's cutting diameter to the small diameter of the recess.
When making the final cut for the cutout, be sure to support the cutout piece so it (AND your router!) doesn't fall through the hole as the last bit of wood is cut away. The easiest way to do this is simply lay the workpiece on a sacrificial surface - even corrugated cardboard will do - and adjust the router bit's cutting depth to just slightly more than the workpiece's thickness.
Dale
All of the previous responses gave good advice. It's probably worth your effort to review previous threads where this general topic was discussed:
http://www.diyaudio.com/forums/equi...le-jig-limited-compatibility.html#post4344730
http://www.diyaudio.com/forums/construction-tips/271242-custom-circle-jig-dewalt-compact-router.html
http://www.diyaudio.com/forums/multi-way/257120-open-baffle-3-way-speakers.html#post3946862
http://www.diyaudio.com/forums/construction-tips/247290-cutting-circles-jig-saw-2.html#post3929167
The recess (or shelf) can be cut after the main cutout. Use a bearing-piloted bit, with the bearing guided along the edge of the main cutout. The bearing RADIUS should be smaller than the bit's cutting RADIUS by the desired width of the shelf. However, I probably wouldn't use this method.
Instead, I'd make an initial pass with the circle jig's outside cutting diameter adjusted to the large diameter of the recess, and the bit depth adjusted to the depth of the recess. Then, decrease the jig's cutting diameter to the small diameter of the recess.
When making the final cut for the cutout, be sure to support the cutout piece so it (AND your router!) doesn't fall through the hole as the last bit of wood is cut away. The easiest way to do this is simply lay the workpiece on a sacrificial surface - even corrugated cardboard will do - and adjust the router bit's cutting depth to just slightly more than the workpiece's thickness.
Dale
Router - without a doubt.
Do the recess first (With 1-2mm larger OD than required) then proceed with the driver opening. Dont go full depth on one go, do several passes.
When you are through leave a "gap of material" on 3 places around the circumference that will hold the cutout in place untill you get all the way around. These 3 bridges can be cleared with regular hand tools afterwards.
Flip the panel over and route a 45deg bevel edge.
🙂
Do the recess first (With 1-2mm larger OD than required) then proceed with the driver opening. Dont go full depth on one go, do several passes.
When you are through leave a "gap of material" on 3 places around the circumference that will hold the cutout in place untill you get all the way around. These 3 bridges can be cleared with regular hand tools afterwards.
Flip the panel over and route a 45deg bevel edge.
🙂
Thank you everybody for being so helpful, a bit more confident now and yes mdf dust does go everywhere, after building the cab the garage looked like something out of a horror movie!!
With practice and Zen you can get pretty good cuts with a jigsaw. But the router is always cleaner. 🙂
I've used 1/4" & 1/2" bits with good results. 1/4 is faster. As others say, make several passes.
I've used 1/4" & 1/2" bits with good results. 1/4 is faster. As others say, make several passes.
Jumping router can also happen when trying to plunge straight down more than a few mm with a straight sided cutting bit. They tend to not cut totally across the bottom, leaving a small "pip" in the centre. I now use a 2 flute end mill (slot drill) (similar to pic in post 3) for this reason as the 1/2 inch router can easily munch through 9mm+ MDF at a time.
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36mm MDF - not for the faint of heart with a jigsaw, and if you want to rebate, your through hole needs to be perfect
did that sound kinky?
did that sound kinky?
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yup absolutely all my bits are straight sided sadly, i was only going down 5-6mm at a time BUT once you've got like 20mm+ of the cutter ((1/4") in there things get real bouncy and sure I got a jump, my collet is worn from work like this in the past and the vibration let the tool get loose and like I say I wasn't sitting hard enough on the thing!! well after that I stopped and checked the collet was still tight every half rev or so, need to get a new collet now, hope I can still get it, I reckon my routers about 15 years old Bosch ! Ebay here I come hahaha yeah all my tools are old coz I keep replacing bearings n things 🙂 once again thanks so much for the help 🙂
That's where the massive production routers come into their own, particularly something with a plunge base - the PC7539 is actually a whole 7lbs heavier than the fixed base version, and doesn't much suffer from the chatter / vibration problem.
Of course, you gotta do a lot of routing to justify having one of these in your kit, and you can still easily fracture over stressed bits - interesting shrapnel that can make
Sounds like it all worked out for you, with minimal unintended consequences - sooner or later you have to write off damage as "cost of doing business"
Of course, you gotta do a lot of routing to justify having one of these in your kit, and you can still easily fracture over stressed bits - interesting shrapnel that can make
Sounds like it all worked out for you, with minimal unintended consequences - sooner or later you have to write off damage as "cost of doing business"
Trying to force the router to smash the MDF where it is not cutting due to the "pip" will cause major vibration, wearing bearings and loosening collets. Once you pass that initial few mm then it is trying to smash the MDF all the way after. Really not good. Get the correct bit and you won't need to press down anything like as much either.
Get yourself one of these.
NEW 1/2" (0.5 INCH) DIAMETER SOLID CARBIDE END MILL SLOT 2 FLUTED 2 FLUTES CNC | eBay
Or even better would be a 1/4 inch or 8mm one with long shaft. They are harder to find though.
Get yourself one of these.
NEW 1/2" (0.5 INCH) DIAMETER SOLID CARBIDE END MILL SLOT 2 FLUTED 2 FLUTES CNC | eBay
Or even better would be a 1/4 inch or 8mm one with long shaft. They are harder to find though.
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Nope as I stated before i was only doing 4-5mm depth cuts, the comment about holding down the router was meaning holding down the tool firmly against the work to stop it jumping up when the tool is deep in the work, I am afraid the tool in your link is far to short and very expensive!! I use a 1/4" tool, the same size as the shank, its a cheap diy router not a pro job 🙂
Ah yes plunge a few mm then go round, sorry should have realised you meant it that way. In that case your cutter should be ok.
I thought the price was OK! I've found the cheap router bits lose their edge very quickly. A big problem on faced chipboard but not too bad on MDF.
I use a B&Q or JCB 1/2 in router, nothing too esoteric. Just took my time to find one with a plunge mechanism with no slack! The weight of it probably makes it easier for me. Looking to get a Bosch or similar handheld 1/4 inch router though as the big ones can be a bit unwieldy.
I thought the price was OK! I've found the cheap router bits lose their edge very quickly. A big problem on faced chipboard but not too bad on MDF.
I use a B&Q or JCB 1/2 in router, nothing too esoteric. Just took my time to find one with a plunge mechanism with no slack! The weight of it probably makes it easier for me. Looking to get a Bosch or similar handheld 1/4 inch router though as the big ones can be a bit unwieldy.
36mm with a jigsaw, lol, to me cutting 18mm is slow and I use good quality blades and pendulum. Also, I notice the blade has a tendency to warp inside the cut to one side, one needs be very precise to avoid this and get a clean cut in general.
I would stick to a router with a very good cutter and the thinnest possible, 6mm or so to speed up the cutout.
I would stick to a router with a very good cutter and the thinnest possible, 6mm or so to speed up the cutout.
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