1st build scavenging results.

[compfranon]

Hi,

I have been busy scavenging materials for a 2' x 2' router to cut wood/acrylic aluminium would be a nice to have. Starting with a simple moving gantry type design made from Aluminium extrusion, or plate if more rigidity is required.

Spindle will be one of the Kress models, haven't decided which is most suitable at this early stage.

Axes will run on linear rails 16/20mm dia, still to source/buy.

X axis ballscrew 0.75" dia x 3mm pitch 8 start thread (21.25 lg thd)
Y axis ballscrew 0.50" dia x 3mm pitch 8 start thread (19.25 lg thd)
Z axis - working on it

Axes control will be via Pc using Mach3

Just acquired 3 x Compumotor S57-102-M0 complete with DRC E57 C153/421 encoder. Looks like 110v supply.


A few questions to help me on my way:

Are these motors ok for my general requirements.

Do/Should I use the encoders or save for later build (i'm sure there will be one - bigger)

Is a parallel port driver card suitable for this build, what should I look out for, or can someone give me a fingerpoint to a suitable make/model.

Based on dimensions above what is preference for linear rail diameter.

How do I determine most suitable spindle motor

I'm sure there will be a load more questions, but these will help me understand if I have the right combination of useful bits, and what I still need
to source.

Appreciate any help or guidance

[lunchtrayrider]

do you know how much z-clearance travel you will want? on my build this was really the defining thing. also settling on actual routable area will help nail down dimensions. once you decide on x-y-z actual router movements then everything can build out from that.

[compfranon]

do you know how much z-clearance travel you will want? on my build this was really the defining thing. also settling on actual routable area will help nail down dimensions. once you decide on x-y-z actual router movements then everything can build out from that.

Thanks for the reply lunchtrayrider.

For the Z axis I have a 200mm travel "drylin T" rail/slide, not a lot of travel I know, but I think it will be fine. I'm assuming I wont need additional linear rails to support it, just working out how to attach a ballscrew drive to it and a collar mount for the spindle.

As far as X and Y, i'd ideally like to make a unit with a 2' x 3' footprint (suits my shed working area), which allowing for axis configuration should give me roughly a 1.5 x 2.5 routable area, which I would be happy with.

[johnmac]

I take it you mean the steppers came with the drivers? If so, be sure they can receive step & direction signals. Some Compumotor drivers use serial commands. I believe the 102 in the model number is the in-oz rating. A bit small, but may work. Mach does not support encoders, so if they cannot be wired to the driver, they won't be used.

Most DIY machines the size of yours have about 3-4 inches of Z travel. More Z travel will need a stronger frame to combat flexing. Even big machines often have only about 6 inches of travel.

As far as rails go, try to use supported rails. Unsupported rails can flex. By the time you discover you have a flexing problem, it can be a real challenge to correct.

Good luck, and keep us posted!

John

[compfranon]

I take it you mean the steppers came with the drivers? If so, be sure they can receive step & direction signals. Some Compumotor drivers use serial commands. I believe the 102 in the model number is the in-oz rating. A bit small, but may work. Mach does not support encoders, so if they cannot be wired to the driver, they won't be used.

Most DIY machines the size of yours have about 3-4 inches of Z travel. More Z travel will need a stronger frame to combat flexing. Even big machines often have only about 6 inches of travel.

As far as rails go, try to use supported rails. Unsupported rails can flex. By the time you discover you have a flexing problem, it can be a real challenge to correct.

Good luck, and keep us posted!

John

Thanks for the reply John,

The stepper motors had the encoder attached, I have since disconnected them, as for a first build I don't want to add more complexity or controller issues.

I checked the manual and it reports the following:
Rotor Inertia oz-in2 = 1.69
Static Torque = 125 oz-in
I haven't got down to studying stepper motors in detail yet, is this value ok, or what should I ideally be looking for.

If the steppers are OK, what driver board should I opt for, bearing in mind I plan to use Mach3 to drive.

I looked at the supported rails last night, and can understand fully the benefits, also looking at using steel plate with multiple bearings as used in one of the other builds in this section. Not sure which is most appropriate.

Really appreciate the comments, all new ground to me.

[ilya]

Not sure if 125 oz-in is enough torque. It should work ok but I don't know how it will cut aluminum... I'd personally look for the steppers in 200-250 oz-in range. But with your ballscrews the less-beefier stepper might work fine though.

I'd leave encoders out for now. Once you make your machine you can always connect them afterwards. It's better to move in small steps. Encoders set-up is just another hassle right now.

Kress spindles are good. Look at their new 1050FME that can go down to 5000 RPM. Especially if you're planning to machine metals. You'll desperately need low RPMs for metals! The only disadvantage of new 1050 is that its maximum is 25000 RPM which might be too slow for engraving some materials. The old 1050 can do from 8000 to 32000 RPMs, so you have to choose which one you want.
Note though, that Kress officially doesn't recommend its router for metals, but mine is working just fine

____________________________________________________

My DIY CNC machine plans at www.8020CNC.com

[compfranon]

Not sure if 125 oz-in is enough torque. It should work ok but I don't know how it will cut aluminum... I'd personally look for the steppers in 200-250 oz-in range. But with your ballscrews the less-beefier stepper might work fine though.

I'd leave encoders out for now. Once you make your machine you can always connect them afterwards. It's better to move in small steps. Encoders set-up is just another hassle right now.

Kress spindles are good. Look at their new 1050FME that can go down to 5000 RPM. Especially if you're planning to machine metals. You'll desperately need low RPMs for metals! The only disadvantage of new 1050 is that its maximum is 25000 RPM which might be too slow for engraving some materials. The old 1050 can do from 8000 to 32000 RPMs, so you have to choose which one you want.
Note though, that Kress officially doesn't recommend its router for metals, but mine is working just fine

____________________________________________________

My DIY CNC machine plans at www.8020CNC.com

Hi Ilya,

Yep it seems common theory that the motors won't be sufficient, looks like an ad for sale shrotly.

I'm rapidly rethinking my ideas, designing around what I can source aint working, it's going to have to be the other way around. My ballscrews are too small for what I want, and the steppers aren't powerful enough.

I've seen some great designs on here, and to be honest for a first machine it looks like i'm going to go with the tried and tested route. Once I understand the principles and have something I can use to make some of the bits to build the elite for me - then thats the way forward.

Thanks for the info re Kress, I think i'm pretty much decided on the manufacturer, but I guess a future reply to this thread will change that.

All in all i'm really looking forward to getting this going, i'm working on a budget and when I spend it must be on the right bits, and only if I can't get them elsewhere. I've a pile of 8020 heading my way soon hopefully, that'll help.

Appreciate the replies, you've all been here I reckon.

[johnmac]

Gecko drives would be a good choice. They cost more because they give more. This is another area where trying to save money may result in replacing new parts that don't perform well. Gecko puts their drives on sale a couple of times a year.

Be sure to check out the photo gallery section for design ideas. You Tube has a number of videos of DIY CNC routers in action, too.

John

[compfranon]

Gecko drives would be a good choice. They cost more because they give more. This is another area where trying to save money may result in replacing new parts that don't perform well. Gecko puts their drives on sale a couple of times a year.

Be sure to check out the photo gallery section for design ideas. You Tube has a number of videos of DIY CNC routers in action, too.

John

Cheers John,

I've noticed their reputation in many of the threads i've trawled.

I now have a build design in mind, a challenge awaits, it's not the construction it's getting the bits through the door without the missus finding out

[ilya]

compfranon,

I can vote for Gecko with both hands. It has an outstanding value and quality and I don't recommend trying to save on stepper driver.
Check Keiling Inc for good and affordable stepers and PSU.

And yes, you should count in the special condition: wife/girlfriend approval factor

_____________________________________________

My DIY CNC machine plans at www.8020CNC.com

[compfranon]

compfranon,

I can vote for Gecko with both hands. It has an outstanding value and quality and I don't recommend trying to save on stepper driver.
Check Keiling Inc for good and affordable stepers and PSU.

And yes, you should count in the special condition: wife/girlfriend approval factor

_____________________________________________

My DIY CNC machine plans at www.8020CNC.com

Gecko will get my business i'm sure, based on their rep.

I'm now officially concentrating on the hardware side, framework etc. Only burning questions is Do I have to base my design on the length of the leadscrew/ballscrew etc having to be machine to suit a bearing support. or is it reasonably flexible.

[ilya]

People often design their machines based on what they can get hold of. Sometimes there's a deal that's hard to pass and you end up buying a ballscrew and design a machine around that.
ACMEs are much easier since they are easier to cut and are cheaper. With ACMEs you can design first and then go and buy stock screw and cut i as you need.

____________________________________________________________

My DIY CNC machine plans at www.8020CNC.com