First Build-Steel Gantry CNC - Comments on design wanted

[Clive S]

Ahh ahh well I didn't go to school much so that explains that. . . Better get it changed quick before anyone see's it and Don't tell Clive else he'll take the Piss for ever. .

Me take the piss you must be thinking of somebody else. Geoffrey it was good to meet you at the show two years ago and see the pics of the Dreamliner, beautiful job.

[GEOFFREY]

Me take the piss you must be thinking of somebody else. Geoffrey it was good to meet you at the show two years ago and see the pics of the Dreamliner, beautiful job.

Hi Clive, was it really two years ago we met - time flies when you're enjoying yourself. I am currently in the throws of building an 18' fishing boat, converting a fiat ducato van into a camper and re-building and converting two more
PCB machines to cnc routers. Too many projects, not enough time, and speaking from experience "it only gets worse!!! Anyway I shall post the final batch of dreamliner pics today. G.

[JAZZCNC]

converting a fiat ducato van into a camper

I run Ducato's for my business every 3yrs we get new one to just to spite the greedy Tax man. 2 vans ago I liked the van so much I decided to convert into camper.
It was Old shape and 2.8 Engine which suited conversion much better than the new shape because side door was nearer front and the Engine was Brilliant, loads of torque and good on fuel for such large engine. Drive Seat was also Comfy unlike the planks in the new ones.!!

My Son "Jazz" Raced MotoX at the time and we took that Van all over Europe up hill and down dale into nearly every field from Barnsley to Berlin dragging a Large Box van behind and it never let me down. I loved that Van.!! . . . I sold it to My mates retired parents, it's still Loved and traveling around europe so I Hope yours gives the same pleasure I had from building and using.!

[olaff]

Lets compare Apples with Apples here.!!. . . . It's not 3 times cheaper if you buy high grade Cast Ground Steel tooling plate.!!

If builder doesn't have the abilty to machine steel flat then they are in for a world of pain when it comes to accurecy.!

Weight should be a Concern but only in certain cutting conditions. If you require high positional feeds with high velocity direction changes then 90Kg is getting close to stressing steppers. Cutting material like aluminium won't be a problem has the feed rates are low but cutting materials like Mdf etc do require higher feedrates to cut correctly so if your cutting shapes that have high velocity direction changes this is where heavy gantry will show up.
That doesn't mean it will cause you problems and you can't cut these materials but it will mean cutting at lower feeds than could be achieved with motors better suited to the weight. It also lowers tool life and finish quality if your cutting lower than optimum feeds.!

It's like Mr "N" says " Every action as equal and opposite re-action" So heavy means slower or more power.! Cut below optimum means Wear tools quicker.!

Regards the Aluminium Bed then I wouldn't bother if i'm honest. Even when cutting aluminium for anything other than real accurate work (or when requireing flood coolant) then you'll use some kind of Spoil board under the material, often Mdf or Ply, so it's wasted money really.
I wouldn't even go to the trouble of building a torsion box if the frame is strong, which it is.? Some form of stable material like high grade ply wood for a base is all that's needed. Then on top of this have sacrificial board that you surface flat. Even if you go to the trouble of making a torsion box you'll still use a sacrificial board which needs surfacing so you gain nothing over just normal piece of Ply.

Put Matrix of threaded inserts into the lower ply and you have hold down system.

Hi Jazz. Thanks for your comment.

I have done a quick calculation and find that using 20mm Aluminium in the Z could save me somwhere in between 6-8kgs...Its not a lot, but i guess every kg helps. I was of course hoping to be able to use the appropriate feedrate for the different materials...Will it help to gear the X axis different? I was thinking 1/1, but that can be changed.

The biggest problem seems to be that I cant find anyone that sells tooling plate in this country....So I guess i will have to go with 5083 plate if I decide to go for aluminium, and build myself a flycutter for the mill and see if i can get it flat..

Yes I guess I drop the idea about Alminium bed and use mist cooling if needed. The Torsion box idea is that its quick and easy to remove in case I need the full height. The plan was to have treaded inserts in both the torsionbox and on the lower plate that sits directly on the bed.