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compositepro
25-11-2011, 10:45 PM
I have been looking at this for a while and its easy enough to do
I need a high accuracy lathe ,A CNC one I have designed the headstock casting and bedways (to take linear guide rails) and also a large bore spindle to take a D1-4

There are a couple of issues that brought this about namely that small chinese cnc machines which are converted are a bit of a compromise and the boxfords with any kind of capacity are like hens teeth

So I designed my own on the basis that most of the stuff is bought

Linear guide rails
Ballscrews
Pulleys
Belts
Chuck
VFD
Motor
SERVO/Steppers (steppers will be fine)

Spindle is machined and ground

on that basis I can get 3 stress relieved castings made but I have to get them cast in 10s to make them cost effective The costs arent that great but it would be a waste to pay for the castings and then do a one off

Is this something that's interesting or would it be a better bet to but the amadeal lathe bed and headstock and modify from there to suit ,I still think the spindle would be too small using this headstock casting.

Maybe theres a market for a high quality machine or do the mini lathe CNC' conversions provide enough for people into this sort of hobby,light production thing

m_c
26-11-2011, 01:05 AM
I'm interested.
Any chance of some sizes (swing/spindlebore/bed length), and prices?

I've looked at various options, and have come to the same conclusions that converting an existing lathe is far from ideal.

Jonathan
26-11-2011, 01:08 AM
I'm interested.
Any chance of some sizes (swing/spindlebore/bed length), and prices?

I've looked at various options, and have come to the same conclusions that converting an existing lathe is far from ideal.

Same here! Have you got a drawing?
I've already got a perfectly good lathe, but I'd prefer not to convert it for various reasons.

compositepro
29-11-2011, 09:16 PM
Same here! Have you got a drawing?
I've already got a perfectly good lathe, but I'd prefer not to convert it for various reasons.

Hey guys thanks for the replies I think theres scope to actually do something with this
Ideally i could load up some cad models done in Pro E or solidworks
Spindle bore im thinking needs to be about 35 mm
Bed size would be about the size of a mini lathe or sieg s6 size
I just keep looking at the cheap chinese castings and thinking they skimped on the casting mass and the beds are a bit skinny If it was cnc and we used slides (hiwin rails) we could just getthe thing ground and tapped to bolt the lot to the bed

The foundry i have been speaking to does GREY CAST IRON ductile was recomended

Im wondering if it would be wise to use a cartridge for the spindle and just thru bore the casting then the precision part for the preload on the spindle etc would need to be the money part

m_c
30-11-2011, 11:32 PM
C6 sizes about the right kind of bed size, but personally I'd want a bigger spindle bore (i'd like to be able to get 2" bar through).
For the spindle, I'd personally machine my own, as that way I'd get what I'd like (big hole and cam lock!)

One thing I'm wondering, why 3 castings?
Surely bed and headstock are the only castings that are really needed?

Jonathan
01-12-2011, 06:02 PM
I'd want a bigger spindle bore (i'd like to be able to get 2" bar through).
For the spindle, I'd personally machine my own

Once again, same here.


One thing I'm wondering, why 3 castings?
Surely bed and headstock are the only castings that are really needed?

Perhaps tailstock or saddle? But as you say they don't have to be cast.

So roughly 24" bed length which I'm pretty sure is short enough to machine on a bridgeport. Is surface grinding strictly required since it's only to mount the profile rail, it's not a running surface? Just needs to be accurate...

compositepro
01-12-2011, 09:20 PM
Once again, same here.



Perhaps tailstock or saddle? But as you say they don't have to be cast.

So roughly 24" bed length which I'm pretty sure is short enough to machine on a bridgeport. Is surface grinding strictly required since it's only to mount the profile rail, it's not a running surface? Just needs to be accurate...

The third casting was indeed for a saddle I'm trying to get the saddle casting to also mount the spindle casting for a mill with vertical hiwin rails

So it can accept the slides for a lathe but it could also do double duty in that I could take the spindle casting dowel and bolt it on and use the same casting for the mill

I havent ruled out epoxy granite for the bed but feel it isnt needed on a hobby size machine its not worth it,Ive done epoxy granite before for a company called zeiss over in germany ,they were damn accurate machines but hey as hobbyist or gor precision engineering it seems we might get a bit hung up on how accurate the machine is

The head casting could take a bored through hole Insert a ground master and moglice it to take a cartridge spindle.

The actual casting cost for the head is 37 quid each and the saddle 17 quid im expecting the bed to be a bit more based on him getting back to me, however the grinder i qot a quote from in sheffield will segmentally grind then line grind the A datum top and B datum foot of the bed casting flat to within 0.05 for 25 quid which seems damn reasonable.

My weak area is electronics I have seen these electronic leadscrews that let you program a pendant to machine instead of using full cnc control I would liketo have some manual control of the lathe without it being connected to a pc using MPG'S TO DRIVE THE STEPPERS does anyone know anything about this?

Ill also cross link this post/ question over on another more electronically oriented part of the forum.

luke11cnc
04-12-2011, 10:20 AM
I might be interested

But would like to see a drawing first

James

elfinjnr
13-12-2011, 06:07 PM
I may be able to help. I have a foundry in my garage. I can do the old cope and drag or I can vacuum loss foam castings.
I'm set up for doing development work on my race bikes so one-off isn't an issue. I'm in Grenoside by the way.

m_c
13-03-2012, 03:07 PM
Compositepro, did you ever get any further with this?

boldford
27-04-2012, 03:43 PM
I'd like to see a follow up to this. I thought the foundry was asking a lot for the castings though.

Robin Hewitt
27-04-2012, 04:47 PM
I may be able to help. I have a foundry in my garage. I can do the old cope and drag or I can vacuum loss foam castings.
I'm set up for doing development work on my race bikes so one-off isn't an issue. I'm in Grenoside by the way.

How come nobody bit his arm off? Is it too late? Has he gone? Come back Elfinjnr, all is forgiven :beer:

elfinjnr
27-04-2012, 06:44 PM
Still here Robin.
I'll do patterns and casting in exchange for work on my miller conversion.
Just contact me with what you need.

boldford
27-04-2012, 08:05 PM
Still here Robin.
I'll do patterns and casting in exchange for work on my miller conversion.
Just contact me with what you need.What materials do you cast and what's the maximum weight?

Robin Hewitt
27-04-2012, 09:37 PM
Still here Robin.
I'll do patterns and casting in exchange for work on my miller conversion.
Just contact me with what you need.

A trade? :beer:

I can cut 2.5D to better than 1 thou in mild steel and aluminium on a good day. Can you make iron axle boxes for my cannon? A hollow truncated cone about 35cm long. See pic.

I lost the patterns last time I got them cast. As far as I know they are still in his bloomin' garage up North, I never could seem to dislodge them.

Jonathan
27-04-2012, 09:47 PM
I'm sure I can think of something I want casting!

Can't cut parts to 1 thou, but I can cut anything up to 1700*740*400mm in aluminium on my router.

elfinjnr
27-04-2012, 11:38 PM
Non ferrous is my bag. The furnace is 600,000BTU so its capable of doing iron. The issue is lifting that weight as I work with a crucible. I'm sure within the DIY casting, a cupula would be better as you can tap straight into the mould (if your good). I can get one offs done in a few steel/iron foundry's in Sheffield.
The popular misconception is that iron is easy. In reality its the hardest. Personally I'd use alloy or brass every time. Much easier and cheaper to do.
Casting weight is what ever I can lift. 30KG at 800C takes a bit of bottle though.

compositepro
29-04-2012, 06:45 PM
Hi all been busy with other stuff ,drawing up castings on pro engineer and playing with cast epoxy carbon fibre and some sand and rocks ,which is technology I have used before ,I do need to get down to see elfin (i still got your number fella) plus worklife has been taking precedence

oh almost forgot i came across these

http://www.klippfeld.at/frame_en/bilder.php?id=10&maschinen=dreh&produkte=zusatz

and they dont cost too much to buy