Design Help Pt2 Required for CNC design/Build

[MikeyC38]

Thanks Jonathan for the additional comments and feedback. More than 1 person saying the same thing is always encouraging!
I am pretty much committed down the existing gantry route because I already have the ballscrews in hand and can't afford to buy anymore at the moment. My earliests thoughts on this was a metal version of the twin ballscrew- belt drive Solsylva design. I accept that the machine may have some limitations with aluminium milling but as this is a tertiary requirement, then I can live with that compromise for now. Wood, GRP, Plastic and CFRP are the priority at this time, hence the size of the machine in the Y axis. I am looking to source aluminium toolplate (6082 T6) and have found a reasonably priced source in Milton Keynes (MetalFast) but that was awhile ago so I will need to recheck.

Kind Regards
Mike

[Jonathan]

I am looking to source aluminium toolplate (6082 T6) and have found a reasonably priced source in Milton Keynes (MetalFast)

Aluminium warehouse has tooling plate which may be cheaper? It's on the website in the same place I linked to earlier. They call it EcoCast.

[JAZZCNC]

I am looking to source aluminium toolplate (6082 T6) and have found a reasonably priced source in Milton Keynes (MetalFast) but that was awhile ago so I will need to recheck.

AW is good like Jonathan says but you really only need tool plate quality in just a few key places, like the Z Axis front/rear plates or for the Bed etc.

Things like gantry sides and general end plates or bearing brackets, motor mounts etc can be got from cheaper flat bar stock, still 6082 T6 just not machined perfectly flat.
The wider width's of flat plate stock can some times come slightly cupped but for none critical stuff or if machining several parts or brackets out of the width then it's not really a problem. . . Often just a quick surface will take away any cup. . . .Thou I must say the last few 300mm wide lengths I've had to deal with have been quite bad. The one I'm using at the moment is particulerly bad and if it wasn't for the fact I was cutting it up into smaller components then it would have been going back.!!

[John S]

Agree John but to be honest I've always found it works out cheaper for small Qty's buying from AW. It seems unless your buying from them on a regular basis as business in decent Qty they load up the price.?

Jazz,
To be honest I don't buy large quantities but buy just what I need unless it's small section and then it doesn't pay to get a bar cut.
I have to rely on their delivery service as my nearest branch is Lincoln, delivery is a reasonable £7.50 no matter what but their rep tells me that if I'm ever in the area to call in and take advantage of offcuts they have lying around.

Not going to happen with me but others who are not so tied to a workshop all working hours could score on this.

[wiatroda]

Worth giving these people a call.
http://www.ascmetalsgroup.com/northampton.html

But please check price first.
I bought 500mm long 2" aluminium round bar from ASC wolverhampton branch and paid £34 for it. AW price £62 for 2000mm long. So much overpriced. As an addition it was the worse piece of metal I've ever had .Totally un-machinable. Still have this piece of c.... in a garage.
It was first and last time I bought from them. :cry: Very disappointed

[JAZZCNC]

As an addition it was the worse piece of metal I've ever had .Totally un-machinable. Still have this piece of c.... in a garage.
It was first and last time I bought from them. :cry: Very disappointed

It wouldn't be sat in my Garage.!. . . It would have been bounced back at them. . . . Like I tell my customers If you don't tell me about problems I can't fix them.!
Thou I prefer customers don't have cause to complain in the first place I much prefer customers to complain in a polite manner rather than not so I can give a replacement has well as highlighting any potential problems which then get corrected.

[wiatroda]

[QUOTE=JAZZCNC;26511 Like I tell my customers If you don't tell me about problems I can't fix them.!
Thou I prefer customers don't have cause to complain in the first place I much prefer customers to complain in a polite manner rather than not so I can give a replacement has well as highlighting any potential problems which then get corrected.[/QUOTE]

You're absolutely right. Like your approach.
The fact is I, as a customer agreed to pay this price (mostly bcos of unawareness of market prices) so there is no reason for price promise return. I used a bit of it, turning it first. If I wanted to knit aluminium jumper swarf would be perfect for this purpose.
Then I broke few 2mm drill bits trying to drill it -different speeds, feeds various lubricants then gave up. When making my timing pulley video (drilling way) I used free-cuting ally- no probs at all.
Anyway I'll keep it in any case- may be useful some day.
Next time I'll check prices first before making any hasty shopping. Just didn't expected price to be so sky-high-different than from other suppliers.

[JAZZCNC]

Next time I'll check prices first before making any hasty shopping. Just didn't expected price to be so sky-high-different than from other suppliers.

Ye I know it really feels like a kickin the nuts don't it when you find it much cheaper else where.! . . . On this point when it's so blatantly over priced I agree with not going back. . . we all need profit to survive but then there's profitering pirecy.!! . . . .That's unacceptable to me too. . . .I was mainly referring to the bad quality of the material.

Like I said to John-S I've found with larger metal suppliers like ASC that if your not a company or don't buy on regular basis in decent Qty's they load the price.!
Fortunatly I am Vat registered and thou my main business hisn't engineering related I do get away with out price loading for awhile but because I don't buy often it soon starts to creep up.!! . . . I don't mind paying slightly higher prices for smaller qty's or tariff Qty based charging but it should stay constant at least.!. . . This piss's me off.

[m.marino]

Mike,

Jazz and I designed a single ball screw machine and when it all came down to it the cost for the pulleys and belts where actually more then going the twin screw route. Now I have to get a second parallel port card to allow me to bring the 4th axis on line and set up a second BOB and driver set up. But outside of materials this is not really a problem when using Mach3. Good luck and hope all things go well.

Michael

[routercnc]

Hi Mike
Good to hear someone getting use out of my spreadsheet. Nice to put something back into this forum.
Just a comment on the x axis bearings. When mounted on their side it does make for a neat installation but be aware that because the blocks are open (sort of C shaped) that they will open up slightly due to the gantry mass and to a less extent the cutting forces. I've not done the calcs but suspect the effect is small so don't panic. Interested to hear if anyone has worked out how much they deflect for a given side load (or vertical in this case) or has experience of this orientation.

As for twin screw - I have a gantry about 600mm wide with a single ball screw and I can rock the ends of the gantry back and forth by hand up to about 1mm if I push hard. Having said that I can happily machine balsa, liteply and ply and they come out at the right sizes. But I would still say twin screw is better and would like to upgrade when funds allow because I could then up the feedrate.