El Beast - Initial design phase, comments and critique welcomed!

**Chaz** · 26-09-2017

Originally Posted by Desertboy

At prices of Tufnol I'd glue it to a 12mm sheet of mdf then you can mill through the whole lot screw wasting any.

If you have issues with losing 12mm of travel on the Z then you really have issues lol

Problem is that MDF absorbs fluid and 'pulls' apart.

**Davek0974** · 26-09-2017

Yep, MDF is pretty duff for metalwork, great for woodwork.

At these prices, has anyone priced up a slab of aluminium?
Its pretty reasonable in 12-15mm thicknesses.

**Chaz** · 26-09-2017

Originally Posted by Davek0974

Yep, MDF is pretty duff for metalwork, great for woodwork.

At these prices, has anyone priced up a slab of aluminium?
Its pretty reasonable in 12-15mm thicknesses.

Oddly, was thinking the same. £86 + VAT + Del for 12mm tooling plate at 650 x 450. Normal plate is still £75.

**Edward** · 26-09-2017

Yes, similar prices. So what's the attraction? Is Tufnol easy to skim, I bet it skims like butter and really fast, probably quite messy, though not as messy as MDF and harder?

**Zeeflyboy** · 27-09-2017

Tufnol is a brand name, Kite is their equivalent product. Tends to be a bit more pricey than the generic SRBP... I've been buying attwater brand from ebay.

As for why it's better than alu, it's probably not really! It does skim very quickly and easily with minimal mess (I skim 0.3mm at 6000mm/s using a single flute 10mm cutter)... I like to cut past the work piece in general so I set a cut through of around 0.2mm which then gets completely cleared out at the next 0.3mm skim.

The main advantage to my mind is that it's softer than alu so more forgiving of plunging down into it quickly so for drilling/tapping it's quicker. Also if cutting CF/FR4/G10/whatever then the fishtail burrs I use for that wouldn't like cutting into alu below the piece but they don't care about cutting into SRBP.

Alu can also leave a bit of an upward edge/burr where it's been cut which might mess with your perfect level bed until the next skim. SRBP doesn't leave any burr that I can see.

Both would be perfectly valid, I just tend to use SRBP for the above mentioned reasons. It is also cheaper than tooling plate... eg a board of 600x400x15mm is £50.46 vs £99.36 for the same size of tooling plate from Alu warehouse (both including VAT). That's half the price... adds up when you consider it's a sacrificial board that your machine will consume over time.

I used a 12mm board which is a bit cheaper than the 15mm... I think it will be too full of holes before I skim it down to a height that's unusable, so there's probably a balance to be found between over-paying for a thicker board that won't be used to it's potential before becoming too full of holes. Will depend on how big your bed is and how hole intensive your work is!

It is also worth considering that you don't necessarily need a piece to cover your whole bed, only big enough for the largest piece of work you need to hold down.

**Edward** · 27-09-2017

Thank you Zeeflyboy, you are very helpful and I see your logic. The piece of SRBP that I got has slight burring at the edges from the cut, easily removed with a light touch of sandpaper. I also got the same Attwater brand.
Edward

**Chaz** · 27-09-2017

Originally Posted by Zeeflyboy

Tufnol is a brand name, Kite is their equivalent product. Tends to be a bit more pricey than the generic SRBP... I've been buying attwater brand from ebay.

As for why it's better than alu, it's probably not really! It does skim very quickly and easily with minimal mess (I skim 0.3mm at 6000mm/s using a single flute 10mm cutter)... I like to cut past the work piece in general so I set a cut through of around 0.2mm which then gets completely cleared out at the next 0.3mm skim.

The main advantage to my mind is that it's softer than alu so more forgiving of plunging down into it quickly so for drilling/tapping it's quicker. Also if cutting CF/FR4/G10/whatever then the fishtail burrs I use for that wouldn't like cutting into alu below the piece but they don't care about cutting into SRBP.

Alu can also leave a bit of an upward edge/burr where it's been cut which might mess with your perfect level bed until the next skim. SRBP doesn't leave any burr that I can see.

Both would be perfectly valid, I just tend to use SRBP for the above mentioned reasons. It is also cheaper than tooling plate... eg a board of 600x400x15mm is £50.46 vs £99.36 for the same size of tooling plate from Alu warehouse (both including VAT). That's half the price... adds up when you consider it's a sacrificial board that your machine will consume over time.

I used a 12mm board which is a bit cheaper than the 15mm... I think it will be too full of holes before I skim it down to a height that's unusable, so there's probably a balance to be found between over-paying for a thicker board that won't be used to it's potential before becoming too full of holes. Will depend on how big your bed is and how hole intensive your work is!

It is also worth considering that you don't necessarily need a piece to cover your whole bed, only big enough for the largest piece of work you need to hold down.

I agree with this. The other option as a middle ground might be some good plywood. Ive got some and will use it and see how it goes.

**Zeeflyboy** · 27-09-2017

So re-visted my end plates with the correct size stock this time...

I also tweaked the designs a little, adding a port for the limit switch wire to the top plate and changed the bottom plate to accept a standard FF12 bearing mount (along with some room for adjustment).

(correct size!!!) stock:

First op done and bolted down

Top side ops done

Bottom sides:

And the back section of the Z-axis is looking a bit more complete! Still needs limit switch installing, side plates and seals machining up, then I can move on to the main front plate and tramming plate.

Good view of top seals:

**Chaz** · 27-09-2017