BuildingAfloat

[Robin Hewitt]

If strapped for cash you can buy a straight shank ER collet chuck and a couple of bearings on ebay for very little, then add whatever motor you can turn up. If you want to cut aluminium or steel, rather than vapourise it, 2-3000 rpm is good.

[BikerAfloat]

Hi Robin,

If strapped for cash you can buy a straight shank ER collet chuck and a couple of bearings on ebay for very little, then add whatever motor you can turn up. If you want to cut aluminium or steel, rather than vapourise it, 2-3000 rpm is good.

I had been thinking along those lines as a serious option for the future, there is a thread I have seen where a gentleman is doing just that (Ah found the thread again: http://www.mycncuk.com/forums/diy-pr...le-design.html). Prior to seeing that I was struggling to work out how to do the collet and spindle. I was totally unaware of the ER spindles! I probably have a suitable motor somewhere in my Dad's shed.

Thank you very much for the suggestion.

Cheers,

Geoff.

[BikerAfloat]

Just found this on eBay @ Tousdiamants Diamond milling machine W12 collet spindle ( schaublin aciera sixis | eBay

Attachment 6512 Already @ £82!!! an unknown quantity, so not going to buy it. However this idea seems is very much do-able.

The link I posted earlier is using an RC plane motor, These are very very grunty for their tiny size, but are still in the 10s of thousand rpm range.

A quick look at "typical" 1/4HP (180W) single phase motor on ebay gave me 220mm dia (way too big to be practical) and is as heavy as a very heavy thing. Not after massive depths of cut as max material thickness I envisage in Ally is 30mm* and maybe 2mm (maybe 5mm) in steel.

*First job will be single piece motor mounts when I can trust myself and the machine!

A 24v 200w electric scooter motor:



e scooter electric 24v 200w Motor belt drive escooter | eBay

It has a what seems like a "too good to be true" new price of just £26 on eBay and from the size of the wires is relatively diddy. It gives 2700rpm, which is in the right ballpark now! Presumably these are man enough, they lug humans around!

Main concern is with Duty Cycle, any thoughts?

So...

ER20 Long shank collet roughly £20
2 x 6004 2RS Bearings £10
Scooter motor £30
24V 10A Power supply roughly £30
Some pulleys & a belt say £30 all in (Might even have some suitable somewhere in Dad's shed
Might have material for holding bearings and making motor mounts

Downside, simply cos I wanted to do this myself...

Would need someone to do the machining for me.

With stepped pulleys, I guess wiring the motor direct to Power Supply with a switch and a link to the machine E-Stop would be fine.

£120 say £150 tops, definately do-able, especially as it would be close to "best practice" for metal.

Obviously collets to get as well, but since it's ER20 only 1 set needed if I go 2.2kW WC eventually.

Any ideas for a 240v motor, minimum power and so on?

or is the Scooter motor idea viable? Bearing in mind Steppers are also often run this way!

Cheers,
Geoff.

[JAZZCNC]

I'd look for a DC tread mill motor far more powerfull with good duty cycles.!

[BikerAfloat]

What an excellent idea Jazz

Plenty on eBay for <£30 I can rob power supplys, motor & speed control from a complete machine!

Gonna check Freecycle to!

Cheers,
Geoff

[BikerAfloat]

Hi All,

After some more reading and some hard thinking, here is the Mk2 machine (progress so far):



Went back to the drawing board completly, re-assessed the space and scaled the machine to what I think I can get away with, rather than basing the machine on the A3ish size previously.

Ive used 5mm Wall Steel RHS as that should be good for the tapped threads to hold down the rails.

Bottom Cross members: 120x60x870
X Rail Supports: 120x80x900 with 900mm SBR25 Supported Rails
Ballscrew Supports: 80x40x220
RM1605 Ballscrews on all Axissss.
Gantry "Feet": 80x40x200 5mm Wall Steel RHS with 2 x SBR25 Bearing Blocks
Gantry Cross Member: 80x80x870 with 2 x 700mm SBR25 Supported Rails, top and bottom.
Y Axis Ballscrew Supports: 10mm Thick Steel plate
Z Axis Plates: 12mm Thick Steel plate
Z Axis Rails: SBR25 Support rails 300mm long

That makes travel roughly X=780, Y=480, Z=100

Y & Z are driven by 2:1 Belt drives, for the X Axis, I am considering a single belt, 3 pulleys and 2 idler bearings also at 2:1 reduction

That's a 2.2kW watercooled spindle on the Z, though I'm also looking at the Treadmill motor option for low rpms. Just waiting for a suitable treadmill motor to appear on eBay!

Problem with this machine is I'll have to "borrow" a mates workshop to build the frame and pay someone to make some of the other components as they go beyond my skills and equipment, ho hum, not the original plan, but I'd like to build just 1 machine and have it last me.

As you can (probably) see in the image, the Spindle comes outside the X Axis, I have left this as it gives me good travel over the steel box which I plan to use for a base for machining metals.

Most likely welded construction, though bolts still hold some appeal for maintaining a "I built it myself" perspective...

... Just noticed I will have to bolt on the Y axis leadscrew/motor mounts, otherwise I can't get the leadscrew in!

[wilfy]

Hi All,

After some more reading and some hard thinking, here is the Mk2 machine (progress so far):



Went back to the drawing board completly, re-assessed the space and scaled the machine to what I think I can get away with, rather than basing the machine on the A3ish size previously.

Ive used 5mm Wall Steel RHS as that should be good for the tapped threads to hold down the rails.

Bottom Cross members: 120x60x870
X Rail Supports: 120x80x900 with 900mm SBR25 Supported Rails
Ballscrew Supports: 80x40x220
RM1605 Ballscrews on all Axissss.
Gantry "Feet": 80x40x200 5mm Wall Steel RHS with 2 x SBR25 Bearing Blocks
Gantry Cross Member: 80x80x870 with 2 x 700mm SBR25 Supported Rails, top and bottom.
Y Axis Ballscrew Supports: 10mm Thick Steel plate
Z Axis Plates: 12mm Thick Steel plate
Z Axis Rails: SBR25 Support rails 300mm long

That makes travel roughly X=780, Y=480, Z=100

Y & Z are driven by 2:1 Belt drives, for the X Axis, I am considering a single belt, 3 pulleys and 2 idler bearings also at 2:1 reduction

That's a 2.2kW watercooled spindle on the Z, though I'm also looking at the Treadmill motor option for low rpms. Just waiting for a suitable treadmill motor to appear on eBay!

Problem with this machine is I'll have to "borrow" a mates workshop to build the frame and pay someone to make some of the other components as they go beyond my skills and equipment, ho hum, not the original plan, but I'd like to build just 1 machine and have it last me.

As you can (probably) see in the image, the Spindle comes outside the X Axis, I have left this as it gives me good travel over the steel box which I plan to use for a base for machining metals.

Most likely welded construction, though bolts still hold some appeal for maintaining a "I built it myself" perspective...

... Just noticed I will have to bolt on the Y axis leadscrew/motor mounts, otherwise I can't get the leadscrew in!

looks ace to me, although i wouldn't know if you'd done anything wrong.. although i cant see your Y axis ballscrew in the picture

[BikerAfloat]

looks ace to me, although i wouldn't know if you'd done anything wrong.. although i cant see your Y axis ballscrew in the picture

Hi Wilfy, thanks for that, there is no leadscrew on the Y Axis yet, drawing very much waiting for input before I do any more!

Cheers,
Geoff.

[Jonathan]

I notice you've opted for steel plate on the Y and Z axis. The vast majority of people use aluminium instead of steel since it is so much easier to machine, particularly with limited/basic tools. 20mm is a good size for the Z-axis.

You could make the top Y-axis rail longer (820mm ish?) and increase the spacing of the two SBR25 bearings upon it, so the plate the Z-axis bearings are mounted on would be a T-shape. Although not critical since your Z-axis is already a good size, this would increase the rigidity for little extra cost.

What's the plan for the bed?

Hi All,

After some more reading and some hard thinking, here is the Mk2 machine (progress so far):



Went back to the drawing board completly, re-assessed the space and scaled the machine to what I think I can get away with, rather than basing the machine on the A3ish size previously.

Ive used 5mm Wall Steel RHS as that should be good for the tapped threads to hold down the rails.

Bottom Cross members: 120x60x870
X Rail Supports: 120x80x900 with 900mm SBR25 Supported Rails
Ballscrew Supports: 80x40x220
RM1605 Ballscrews on all Axissss.
Gantry "Feet": 80x40x200 5mm Wall Steel RHS with 2 x SBR25 Bearing Blocks
Gantry Cross Member: 80x80x870 with 2 x 700mm SBR25 Supported Rails, top and bottom.
Y Axis Ballscrew Supports: 10mm Thick Steel plate
Z Axis Plates: 12mm Thick Steel plate
Z Axis Rails: SBR25 Support rails 300mm long

That makes travel roughly X=780, Y=480, Z=100

Y & Z are driven by 2:1 Belt drives, for the X Axis, I am considering a single belt, 3 pulleys and 2 idler bearings also at 2:1 reduction

That's a 2.2kW watercooled spindle on the Z, though I'm also looking at the Treadmill motor option for low rpms. Just waiting for a suitable treadmill motor to appear on eBay!

Problem with this machine is I'll have to "borrow" a mates workshop to build the frame and pay someone to make some of the other components as they go beyond my skills and equipment, ho hum, not the original plan, but I'd like to build just 1 machine and have it last me.

As you can (probably) see in the image, the Spindle comes outside the X Axis, I have left this as it gives me good travel over the steel box which I plan to use for a base for machining metals.

Most likely welded construction, though bolts still hold some appeal for maintaining a "I built it myself" perspective...

... Just noticed I will have to bolt on the Y axis leadscrew/motor mounts, otherwise I can't get the leadscrew in!

[BikerAfloat]

Hi Jonathan and thank you for your post,

I notice you've opted for steel plate on the Y and Z axis. The vast majority of people use aluminium instead of steel since it is so much easier to machine, particularly with limited/basic tools. 20mm is a good size for the Z-axis.

Opted for 12mm steel for strength and to keep the overhang low-ish (well low within the restrictions of supported rails), I thought I'd keep the aluminium down to a minimum for stiffness. I'll see what the 20mm gains me in reduced overhang, it might be worth a drop in stiffness over 25mm. What size do people tend to go for?

You could make the top Y-axis rail longer (820mm ish?) and increase the spacing of the two SBR25 bearings upon it, so the plate the Z-axis bearings are mounted on would be a T-shape. Although not critical since your Z-axis is already a good size, this would increase the rigidity for little extra cost.

I had considered that, may look at the drawing again, I have to mount limit switches yet and thought the space could take the mountings for them, that was all.

What's the plan for the bed?[/QUOTE]

I am leaving that open in this sketch, but I have plans for several options:

1) A simple MDF bed with 2 layers, support and spoilboard
2) Aluminium (or maybe even steel) drilled and tapped
3) Open to allow a 4th axis to be mounted
4) A removable T Slotted Steel bed across the front cross member
5) Open to allow me to mount motorcycle engine casings on the bench beneath for engraving

Basically I have left it free to see what develops over time.

I'm hoping with the small overall size and the relatively large size of the frame in comparison, it should be up to most of what I can see me throwing at it... Only time will tell.

Cheers,
Geoff.