welding steel base or just getting aluminium extrusion

[reefy86]

well considering at the moment so far its at £2600 and thats without the bits and bobs to connect it all so i am looking at £3k for 90x90 heavy. And clive i have seen some builds but nobody mentions what sort of extrusion they use in the build. i have even googled it but i am struggling with so many different types to choose from. it looks as if Bosch Rexroth are the best quality but not sure about the ITM range. the ITM only goes up to 8mm t slots where as the BR does 10mm and then there is the light or heavy.

on the cncrouter.com they do the 8x4 pro kits and you can buy the bed frame only for £600 and that machine seems to have good feedback for quality so my guess for that price they have used the lighter extrusions and looks as if they are using the 45x90 but then 45mm seems flimsy.

are most of you bald by any chance? its very stressful lol.

ill keep scrolling the forums and see if i can find anymore info and idea's :)

[reefy86]

I have not seen other threads on this but what is the overall size and the size of the box? Is there any reason you have made this frame in a format which is basically 2 squares/rectangles joined in the middle?

In this one i produced some years ago you will see the box runs full length then all cross members and infills added after. This is the standard format used in industry and how designers would produce a frame. I have made many like this the years on a slab (large surface plate, not a welding table) This ensures the best flatness possible within the constraints of the material.

Attachment 23320

If your frame is as big as it looks and they have a slab that big, then its a fair price in my view if those boxes are as big as they look. Also the way you have designed it as mentioned as 2 squares joined has not helped the costs, it makes it harder to keep it as flat as possible as apposed to having the box run full length,

No reason other then recommendations which proves to be very strong and sturdy, but for those who can weld its not so much of a trouble with mild steel being very cheap but for me having to find someone to weld it for me then all those pieces to weld is costing a fortune.

[reefy86]

I see good old Dean is famous in the united states too :)

[spluppit]

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[reefy86]

I'm going to go down the aluminium extrusion route after all and for a few reasons, the obvious one is i aint welding all that steel and i defiantly haven't got the funds to pay someone that amount as well as having the funds to pay 3 months upfront deposit on a new workshop unit and then the frame on top lol. I know its worth the price what the guy offered but i just can't afford it on top of everything else.

Now there is 2 options and option 2 does have diagonal support i just couldn't be bothered to add them in lol

option 1

copy the cnc pro kit 4896 from cncrouter.com (frame bed only) costing me just under £1k which is using the 40x80 profiles but the heavier ones

option 2

80x120 with less profiles then the 40x80 costing just over £1k but these are the light profiles not the heavy ones

i know its way more expensive then steel but i am not as lucky as most of you with welding skills and i can always add to the frame once more funds come in. personally i prefer option 2 as it looks way more solid but would like your opinion and if and where i should add extra support.

Appreciate the help guy's

[Clive S]

I look after a machine that is built similar to option 2 built by a company with initials like MD and it does work and cuts 8x4 sheets of 6mm MDF all day.

the rack & pinion seems to be fine and the rack is mounted inside the slot on the side of the top rail.

Have you thought how you are going to drive it and what motors etc.

[m_c]

I know you are going on other designs but all this generally means is.... someone that isn't an Engineer or a fabricator came up with a design, made it and it worked, and that then sets a president others follow. That does mean mean its good design all it means is someone proved it worked. In the same breath if that design had been done by someone with a lot of experience then that would have been the president and far easier to get a lot better result.

You'll not last long in the DIY CNC world with sensical observations and comments like that ;-)



Listen to what sluppit has said.
I took one look at your design last night, and immediately wondered how many tonnes you were planning on having on it, and why it wasn't using full length sections on the long edges. It looks to me like you've just kept adding bits, without really thinking about why you would need to add them, and ended up with an over complicated design.

[reefy86]

I look after a machine that is built similar to option 2 built by a company with initials like MD and it does work and cuts 8x4 sheets of 6mm MDF all day.

the rack & pinion seems to be fine and the rack is mounted inside the slot on the side of the top rail.

Have you thought how you are going to drive it and what motors etc.

yeah i already have 90% of the electronics planned out with the help from Dean using high quality ballscrews/hiwin rails/rotating ballnuts for the long y axis. even though i said i was going to copy of cncrouter.com that was just for the bed but everything else will be better and defiantly will be wanting to cut thicker then 6mm all day lol :)

[reefy86]

You'll not last long in the DIY CNC world with sensical observations and comments like that ;-)



Listen to what sluppit has said.
I took one look at your design last night, and immediately wondered how many tonnes you were planning on having on it, and why it wasn't using full length sections on the long edges. It looks to me like you've just kept adding bits, without really thinking about why you would need to add them, and ended up with an over complicated design.

it wasn't complicated until i finished in solidworks and then reality hit :)

[spluppit]

Removed.