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routing translam end grain
routing translam end grain
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Old 27th June 2018, 08:00 PM   #1
robinlawrie is offline robinlawrie  United Kingdom
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Join Date: Feb 2008
Default routing translam end grain

Hi All. ive finally received my cnc cut parts for my translam subs and speakers. it only took 9 months (its hard to hurry along a favour)

at least my alpair dirvers had lots of break-in time (about 1100 hours before i decided i was wasting electricity)

anyway, one of the (many) things i have to do now is cut a pair of circa 6 inch round cutouts into the side of the translam cabinet once its stacked and glued.

these will have a step profile to them and the speakers will be recessed, so the front edge of the hole has to be as clean as possible, as it will be visible.

add to this the fact ive never used a router before ( i purchased a palm router just for this job)

so im looking for any advice on how to proceed..

im planning to make an aluminium sheet circle jig with two diameters, the first i will cut the outer edge of the hole, going down the necessary 1cm.

ill then probably need to do another cut within that one to get the width of the "lip" correct.

once those cuts are done (multiple shallow passes to get a clean finish with my little router)

ill then set the circle jig smaller and do the inner cut all the way through (in multiple passes)

so my questions:

*should i go for a fast or slow speed? no idea.. - i purchased a few draper brand straight router bits.. not the cheapest but nothing special obviously.. reviews were quite good

* should i stop 1-2mm from cutting through, then finish with a stanley knife?
-if i cut all the way through, the circle jig will no longer be supported and i risk a last minute wobble with the router..

other than that vague plan, i have no idea.. im planning to test on a sheet of ply, but obviously that wont be pure stacks of end grain in two directions!

im quite nervous.. it has to go perfect first time :P
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Old 27th June 2018, 08:18 PM   #2
robinlawrie is offline robinlawrie  United Kingdom
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another question i had.. direction of cut vs bit rotation for cleanest cut on outer edge?
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Old 28th June 2018, 07:54 AM   #3
robinlawrie is offline robinlawrie  United Kingdom
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ok bit more reading, seems i want to be using a "downcut" router bit to get a clean cut on the top edge of the cutout? the bits i purchased with my router are all straight cut.


however the source of this advice is somebody referring to cutting plywood in the normal orientation, not end-on and stacked, like i am trying to do..

anyone else actually done this and has suggestions?
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Old 28th June 2018, 06:41 PM   #4
russc is offline russc  England
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I assume you are meaning a trammel with centre pin.
For the final cut through you can make 2 half circle cuts leaving 1cm of material at 2 points diametrically opposite; then you do not lose your centre.
You can cut through the remaining 1cm tabs (knife/saw, whatever).
The remaining stubs can be routered off with a flush trim cutter (top or bottom bearing as you prefer).
Whatever you do, practice on scrap material is always advisable.
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Old 30th June 2018, 03:37 AM   #5
chrisb is offline chrisb
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Location: victoria BC
A few suggestions -

- end grain of translam plywood fabrication is much tougher to route that you might like to think, youíll likely get much better results with a higher horsepower/ heavier router to avoid chatter/ bouncing around
- definitely use a down-spiral / compression cut solid carbide router bit to reduce tear-out- youíll be changing grain directions every few mm.
- itís impossible to have the workpieces too rigidly clamped to as heavy a work surface as you can muster
- use a high toolbit rotational speed and slow / uniform feed rate to yield cleanest results.
- cut ďintoĒ the direction of bit rotation


I have built literally hundreds of pairs of speakers over the last 20 yrs, most from Baltic Birch/ ApplePly, and aside from the factors of cost and time, there more than a few reasons Iíve never done a translam fabrication. OK, thatís partly a lie - the huge waste of material and extra time are definitely included in that decision.
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Old 30th June 2018, 08:01 AM   #6
robinlawrie is offline robinlawrie  United Kingdom
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Join Date: Feb 2008
Quote:
Originally Posted by chrisb View Post
A few suggestions -

- end grain of translam plywood fabrication is much tougher to route that you might like to think, youíll likely get much better results with a higher horsepower/ heavier router to avoid chatter/ bouncing around
- definitely use a down-spiral / compression cut solid carbide router bit to reduce tear-out- youíll be changing grain directions every few mm.
- itís impossible to have the workpieces too rigidly clamped to as heavy a work surface as you can muster
- use a high toolbit rotational speed and slow / uniform feed rate to yield cleanest results.
- cut ďintoĒ the direction of bit rotation


I have built literally hundreds of pairs of speakers over the last 20 yrs, most from Baltic Birch/ ApplePly, and aside from the factors of cost and time, there more than a few reasons Iíve never done a translam fabrication. OK, thatís partly a lie - the huge waste of material and extra time are definitely included in that decision.

Thanks for the advice, very helpful. To be honest i assumed it would be hard, although i admit i didnt consider the size of the router would be an issue.

Im considering taking it to a carpenter, but since they would care less than me, i might be better practising and doing it myself.

Regarding the router bit, ive looked on amazon uk /italia (need a european source), and downcut carbide bits go from 20-30 euros at the suspiciously low end (but still expensive for one small project) , up to hundreds of euros. Hopefully somebody could point me to a decent cheap bit thats available here.

I chose translam construction because i had a design that lends itself to the method, but more importantly, i had a big favour owed by a cnc shop, so got it done for free. I reduced the waste by nesting the small fullrange cabinets inside the cutouts for the subwoofers. Wood utilisation was still a rather feeble 36% so i do agree its a wasteful method.

Anyway thanks again for the advice.. Im still stacking and gluing and i guess ill be cutting a load of strips of ply and gluing up some endgrain test sheets too!
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Old 30th June 2018, 03:35 PM   #7
robinlawrie is offline robinlawrie  United Kingdom
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would an up/down cut bit such as this be ok?

EU_HOZLY 6X25mm UP &DOWN Cut Two Flutes Spiral Carbide Tool Cutters for CNC Router Compression Wood End Mill Bits: Amazon.co.uk: DIY & Tools

has a few good reviews, and the price is more in my ballpark.. but i have no idea if a downcut/compression bit is vastly preferable in my case..
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Old 9th July 2018, 12:39 AM   #8
chrisb is offline chrisb
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Join Date: Aug 2002
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With tooling running at the shaft rotational speeds found in routers, you get what you pay for. Being near the end of my career in a commercial cabinet shop, I can only base my observations/ suggestions on that.

If you don’t / can’t use a top bearing mounted pattern following/ mortising bit, those solid bits can be fine - but be aware they can snap if overloaded by material density or aggressive feed rate. Hopefully you’re out of the line of fire - but do some math on bit speed of at least 10-25K rpm, and the mass / sharpness of broken bit, and well, don’t wanna scare ya, but safety face shield is with every penny.

Larger diameter shafts ( i.e. 1/2” or more), combined with a heavier machine will make child’s play of most heavier load jobs. My personal favourite is the Porter Cable 7518; at over 15 lbs, not a one-handed operation - I tried that once- but with the workpiece securely clamped, she’s a dream to use. We burn out probably half a dozen 1.5HP routers and smaller laminate trimmers a year, but our two 7500 series are well into their teens. It’s the standard motor affixed to the killer Betterley solid surface coving and bevelling jigs.
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Last edited by chrisb; 9th July 2018 at 12:45 AM.
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