7' X 4' Combi

[Jonathan]

If at this stage you can't afford or justify getting a piece of aluminium big enough to cover the whole bed, or strips to cover the bed leaving slots, then I'd say the minimum is a piece wide enough to span the machine and long enough to be useful. That means about 4' by something, maybe 1200x600 would be enough to cover most things. The biggest single aluminium part I've machined on my router was 1015x700x25.4mm and the biggest aluminium 'job' so far has been 1480x715x20mm, which probably doesn't help much with your question as it depends entirely on what you're planning on making. Also these parts were machined when I still had an MDF bed, so if the part wont fit on you're aluminium bed it's not the end of the world. Since your bed will be well supported I see no reason to get more than 20mm thick aluminium.

[Ricardoco]

If at this stage you can't afford or justify getting a piece of aluminium big enough to cover the whole bed, or strips to cover the bed leaving slots, then I'd say the minimum is a piece wide enough to span the machine and long enough to be useful. That means about 4' by something, maybe 1200x600 would be enough to cover most things. The biggest single aluminium part I've machined on my router was 1015x700x25.4mm and the biggest aluminium 'job' so far has been 1480x715x20mm, which probably doesn't help much with your question as it depends entirely on what you're planning on making. Also these parts were machined when I still had an MDF bed, so if the part wont fit on you're aluminium bed it's not the end of the world. Since your bed will be well supported I see no reason to get more than 20mm thick aluminium.

Ideally i would like to cover the whole bed in profile, but the cost i suspect would be well over the top, in fact i dare not look although it wont be as much as it was when the bed was 7' but since i rebuilt the bed length at 6'6"x4'. I would love a complete bed ali with t slots but im not sure i can justify the massive percentage of the final cost.....

So your largest Ali machined part was 1480 x 715. Cheers Jonathan.

Ok any more offerings??


Rick

[JAZZCNC]

Agree 1200x600 would be my minimum if planning on cutting thicker Aluminium has most Single parts will usually fit in that space and only if your nesting several parts will you need much above this. Even thou my 1200x1200 bed is all Ali (slots) usually half of it has piece of MDF or HDPE spoil board on it.

If your cutting thin Ali plate like 3-4mm then you'll probably want more space and be cutting large single pieces anyway. So then again you'll probably find an MDF spoil board will be used for holding and bed saving reasons.!

Part holding is a challenge and can be pain also it can be very part dependent.? You'll find even with an Ali bed you'll use some form of protective material or spoil board between part and bed.!

[Ricardoco]

Agree 1200x600 would be my minimum if planning on cutting thicker Aluminium has most Single parts will usually fit in that space and only if your nesting several parts will you need much above this. Even thou my 1200x1200 bed is all Ali (slots) usually half of it has piece of MDF or HDPE spoil board on it.

If your cutting thin Ali plate like 3-4mm then you'll probably want more space and be cutting large single pieces anyway. So then again you'll probably find an MDF spoil board will be used for holding and bed saving reasons.!

Part holding is a challenge and can be pain also it can be very part dependent.? You'll find even with an Ali bed you'll use some form of protective material or spoil board between part and bed.!

Hi Jazz did you make your slots, if so how or did you buy the plate somwhere if so where. I must admit your 1200x1200 seems like a nice size to me as im unlikely to be machining anything larger... Mind you never say never... If i were to go for a solid plate that size at 20mm thick i would be looking for someone else to drill and tap all the holes as I wouldnt look forward to that..

Rick

[Jonathan]

Hi Jazz did you make your slots, if so how or did you buy the plate somewhere if so where

He used aluminium flat bar, so the strips span the width of the bed with a small gap (12mm ish?) between each strip so you can put a bolt through and use nuts/T-nuts or whatever underneath the bed. Can also skim the strips several times without problems. I went for a single sheet to better contain flood coolant and I'm going to add strips on top to make T-slots.

If i were to go for a solid plate that size at 20mm thick i would be looking for someone else to drill and tap all the holes as I wouldnt look forward to that

50p per hole ;)?

Drilling them is easy if you use the router with a carbide drill - it's tapping that's the tedious bit.

[Ricardoco]

He used aluminium flat bar, so the strips span the width of the bed with a small gap (12mm ish?) between each strip so you can put a bolt through and use nuts/T-nuts or whatever underneath the bed. Can also skim the strips several times without problems.

@ Jazz..(or Jonathan if you Know) Flat bar say 2" wide ontop of what and fixed how??

I suspect when doing the holes i will get one of those tapping attachments if i go for the single plate.

I can streach to a plate 2000 x 1220 x 10mm at a push for under £600 but will that do the job....


Rick

[Jonathan]

@ Jazz..(or Jonathan if you Know) Flat bar say 2" wide ontop of what and fixed how??

Jazz has said previously on this forum:

bed made from 40x16 strips spaced 10mm apart to create Tslots.

But I recall him advising that greater than 16mm thick would have been better, simply for the extra strength and I guess you can surface it more times.

[JAZZCNC]

Hi Jazz did you make your slots, if so how or did you buy the plate somwhere if so where.

Like Jon says used 1.5" x 5/8" (38x16mm) Ali strips with 10mm gaps giving 45mm centres between slots. The slots where cleaned up with 10mm cutter taking the difference away leaving 45mm centres and ensuring parallelism to Axis. (See pics)
Regards drilling and counter bores etc then I clamped the strips in place and the machine drilled and counter bored them in situ. I just tapped the Holes with spiral tap in Hand drill.
My bed frame is 50mm box with braces every 16" which the strips fasten too. The gap between top and bottom of box means no machining or tapping and the T nuts just clamp to under side of strips.
If coolant is need then it's easy enough to make it sealed tray by fastening Ali or galv sheet on underside.

I looked at all ways and at the time this was the cheapest way I could found.

Personally I wouldn't use 10mm has I can flex 16mm at times when clamping hard.

[JAZZCNC]

But I recall him advising that greater than 16mm thick would have been better, simply for the extra strength and I guess you can surface it more times.

Yes thats correct but more for Strength than surfacing, I've only had to surface mine 1 time and that was only 0.3mm ish.?

[Ricardoco]

Ok a little more progress today.


Now that all the alignment has been completed the Left and Right gantry supports have now been seperated.

Rick