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mondrota
14-12-2016, 01:01 PM
Hi all,
i'm new to the forum so excuse me if this post is in a wrong place.
So here is my problem:
I'm looking for a decent material to use for my DIY CNC router cutting bed (working area of 800x480mm). I need it to resist moisture as my router is in a garage that gets really damp during winter, and my current bed (plywood + mdf on top) expands and contracts like crazy.. I do a lot of V carving so a flat bed is a must.
So at the moment I'm considering 20mm thick acrylic or 20mm HDPE sheet. I'm looking to spend up to £100 if possible. The entire bed size is 1100x620mm.

So what do you guys think I should do? I just need a material that will resist moisture and bending.

CHeers, Kamil

Maxakarudy
14-12-2016, 09:24 PM
There is a sign material called Foamex, I use a 19mm thick sheet, you can drill and cut it like MDF, but it's moisture resistant as it's plastic, it's nothing like perspex btw
Martin

mondrota
14-12-2016, 09:27 PM
Thanks Maxakarudy,
Is it also a rigid material that won't deflect much while cutting?

Clive S
14-12-2016, 10:46 PM
Thanks Maxakarudy,
Is it also a rigid material that won't deflect much while cutting?You will need something that you can drill and tap into as well.

Maxakarudy
14-12-2016, 10:47 PM
Yep,
I have an industrial router, that's what most sacrificial beds are made of

mondrota
14-12-2016, 11:39 PM
Ok, so I have 3 options now. I checked this foamex on ebay and it is much cheaper. I can drill holes and glue in t nuts at the bottom. I'm just a bit concerned about the rigidity of this material. It is a light foam material after all..

Maxakarudy
14-12-2016, 11:57 PM
19mm is very rigid, find a local sign company, they might have some to show you and could get you a sheet, Ebay is way too expensive

bobby
15-12-2016, 12:03 AM
Ok, so I have 3 options now. I checked this foamex on ebay and it is much cheaper. I can drill holes and glue in t nuts at the bottom. I'm just a bit concerned about the rigidity of this material. It is a light foam material after all..

How about Rigid PVC BLACK PLATE/SHEET 1520mm x 1300mm X 25mm THICK

ebay item number: 152320149415

Machineable, tappable, solid!

A bit big for your purpose though? Maybe he would cut it??

cropwell
15-12-2016, 12:52 AM
I have got a sheet of 10mm thick paxolin marked out ready to cut to size to fit my machine bed and drill with a matrix of holes 45mm apart (so that they coincide with the T-slots) the holes then have M6 brass inserts pulled into them with a smear of araldite as lubricant. I plan to use this as a permanent sacrificial bed. For the moment I am just making up jigs for each job, like this one

20017

Rob

Maxakarudy
15-12-2016, 09:26 AM
This is my router bed, 3mx2m in 19mm foamex, I cut a grid with 100mm centres for easy reference to keep things square, I cut a lot of sheet material 3-25mm, I prefer to screw things to the bed, in the slot 5mm deep, so there is liitle chance of movement of the panel and clamps are more bulky and can slip.
My machine has a vac bed, however I've learnt of the years it's not 100% reliable to stop movement of the panel, 1 screw up and it's all over, I cut quite a bit of aluminium sheet with mist coolant so don't use the the chip collection system, I do use it on dry materials like perspex & mdf.
BTW I conterbored it to the aluminium slats with Tec screws which are about 10mm from the cutting surface, then milled the bed flat

20019

I have a piece of 19mm foamex 1000x500 I can get it delivered for £50 if you are interested
Martin

mondrota
15-12-2016, 01:00 PM
Bobby,
Thanks for your suggestion, that does look solid but I don't think I'll get it for under £100 even if he does decide to cut it..

mondrota
15-12-2016, 01:03 PM
Martin,
I'm now leaning more towards this foamex stuff. Thanks for the offer but it's just a little small.. I found this listing on ebay at a decent price 171981860453

I'll see if they can supply custom sizes.

mondrota
15-12-2016, 01:21 PM
One more thing, on the picture I think I can see that your foamex is pretty much fully supported (correct me if I'm wrong).
My diy router has 20x40mm profiles running lengthwise and about 10cm apart. I hope this foamex will not sag where its not directly supported?
Cheers

Boyan Silyavski
15-12-2016, 01:44 PM
IMHO there is no better bed than Phenolic. All else will suck water like crazy and will change shape like wood or will crack or... It is the perfect material for sacrificial bed. Plus holds dimensional stability like nothing else for the price. Paper phenolic is ok for the job. If the machine is precise when you say cut to full depth it will slide on top of phenolic and no need to surface it so often.

mondrota
15-12-2016, 01:49 PM
Thanks for your input Boyan,
Do you mean phenolic plywood? Ebay number 162227405235

Or could you find one and post a link/number?

Thanks Kamil

Boyan Silyavski
15-12-2016, 01:59 PM
http://www.ebay.co.uk/sch/i.html?_odkw=162227405235&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR12.TRC2.A0.H0.Xpheno lic+sheet.TRS0&_nkw=phenolic+sheet&_sacat=0

I use 10mm / cause i had some old McDonalds doors/

Maxakarudy
15-12-2016, 02:03 PM
One more thing, on the I think I can see that your foamex is pretty much fully supported (correct me if I'm wrong).
My diy router has 20x40mm profiles running lengthwise and about 10cm apart. I hope this foamex will not sag where its not directly supported?
Cheers

Dunno really, you might have put more support in, but 19mm is really rigid.

Also if anybody hasn't used foamex as a sacrificial bed, they shouldn't diismiss it, every industrial router I've owned has been fitted with it.

mondrota
15-12-2016, 02:03 PM
Thanks, my main concern is that since its plywood coated in something, won't the plywood absorb moisture around the edges and swell?

Boyan Silyavski
15-12-2016, 02:05 PM
Its not plywood coated in sth. Its Tufnol or Pnenolic sheet paper based. I was not saying Phenolic Plywood

mondrota
15-12-2016, 03:39 PM
Looking at the link you posted, all I can see is phenolic plywood. Could you find a listing for the stuff that you are suggesting?
Thanks Kamil

Boyan Silyavski
15-12-2016, 04:47 PM
https://www.directplastics.co.uk/tufnol-sheet/

JAZZCNC
15-12-2016, 05:02 PM
Look for product called Trespa Athlon.
It's Resin based fibre board that is very muck like Pnenolic board but with laminate face. Completely resistant to moisture, chemicals, heat. It's used in place like swimming cubicles, counters for Labs etc.
It can even be drilled an tapped. I use it for Spoil board on my own machine which is constantly covered in cutting fluid. All work is help down by drilling and tapping directly into it or by clamping using holes tapped into it.

Not cheap but extremely resistant and tuff stuff. Nothing better for bed IME.

cropwell
15-12-2016, 05:59 PM
The stuff Boyan and I were talking about is Tufnol 1P13 like as here https://www.directplastics.co.uk/tufnol-sheet. They do all sorts of engineering plastics.

Rob

Boyan pulled up the link just afore me.

mondrota
15-12-2016, 06:27 PM
Thanks, would you say a 12mm thick sheet will be rigid enough for my application?

I had a look at this Trespa Athlon stuff and it's not cheap or easy to come by so I'll pass on that.

JAZZCNC
15-12-2016, 07:04 PM
I had a look at this Trespa Athlon stuff and it's not cheap or easy to come by so I'll pass on that.

That's because you don't know where to go asking.? Try Local Sheet supplier or Shop fitting company and think you'll find they have offcuts which will do what you need. Comes in large sheet sizes 12' x 6' so often have big offcuts.

Boyan Silyavski
16-12-2016, 08:33 AM
Trespa Athlon is exactly the same i was saying plus thin melamine both sides.In fact its exactly what i am using, i told you - McDonald doors Its paper/wood phenolic. because of the melamine could be e bit more expensive than the ones i pointed to.

Though in my experience with laminates, there are 2 more varieties that are looking same as phenolic but they suck water and dont resist so much as it. So i assume that the Trespa Athlon that for sure is phenolic will be the "fire retardant version"

So why you just dont go with the Tufnol 1P13 which is most accessible as price.


And No, it will NOT be rigid enough. Whatever sheet you use apart from steel or aluminum will not be rigid enough that size 15mm . It must be combined on top of sth else.




TRESPA® ATHLON®
Decorative high-pressure compact laminates according to EN 438-4:2005 of thicknesses of 6 mm (± 1/4 in) or greater for indoor applications. Sheets consisting of layers of wood-based fibres (paper and/or wood)
impregnated with thermosetting resins and surface layer(s) on one or both sides, having decorative colours or designs. The surface layers are impregnated with melamine based resins. These components are bonded
together with simultaneous application of heat (≥ 150° C / ≥ 302° F) and high specific pressure (> 7 MPa) to obtain a homogeneous non-porous material with increased density and integral decorative surface. They
are available in the Standard grade (CGS) and in the Fire-Retardant grade (CGF).

Boyan Silyavski
16-12-2016, 08:37 AM
Or go to you r local superstore or airport and steal a toilet door :anonymous:.. As Dean said, think where they could have it. Your best bet is kitchen fitters, they have rests this size from even better and thicker materials. Dont you have an industrial zone there? Look at their trash, ask around. Also any junkyard this could be had for next to nothing

mondrota
21-12-2016, 05:06 PM
Thanks for all your input, I'll see how I get on and will keep you informed.

Dean jeffery
22-12-2016, 02:19 PM
I've been looking for the trespa Athlon stuff, I was quoted £90 plus VAT for a bloody off cut 600x400.

JAZZCNC
22-12-2016, 06:25 PM
I've been looking for the trespa Athlon stuff, I was quoted £90 plus VAT for a bloody off cut 600x400.

I'll drop you some off over Xmas.

Dean jeffery
22-12-2016, 06:31 PM
Cheers mate

mondrota
16-01-2017, 10:31 AM
Ok, I've got my eye on this thing. Just not sure if it's thick enough.
Look at this on eBay http://www.ebay.co.uk/itm/331996752740

Dean jeffery
16-01-2017, 11:21 AM
There is some bigger stuff on eBay but thinner and was used for bogs, so might be full of scratch and sniff.

mondrota
19-01-2017, 10:25 AM
Ok, i bought an old Trespa Athlon lab worktop and man, it's the ducks guts. I didn't realise how solid this is until I started cutting it with a circular saw to get it in the car.
I've got a 2000x700 piece left to sell if someone wants it. It's a 16mm thick sheet.
Thanks to all for their input.

Boyan Silyavski
19-01-2017, 10:30 AM
Great! Also just FIY this stuff is incredible for molds, as it keeps very good dimension and has very good resollution when fine cut with small bits. Say you need some gears made or you design sth. Cut it inside the sheet, then pour PU and there you have it.

Like that: http://lcamtuf.coredump.cx/gcnc/full/

mondrota
19-01-2017, 01:14 PM
Great tip, I'll keep that in mind!

JAZZCNC
19-01-2017, 04:24 PM
Ok, i bought an old Trespa Athlon lab worktop and man, it's the ducks guts. I didn't realise how solid this is until I started cutting it with a circular saw to get it in the car.

Should try lifting 12' x 6' x 20mm weighs more than your car. . Lol