Thinking Of Cnc'ing A Rf45 - Which Steppers?

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Matabele

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Hi all,

I'm a complete noob to the world of CNC and was hoping I could get some advice to point me in the right direction. In terms of capability If I could convert a mill to replicate the capabilities of a Tormach 1100 that would suit the projects I have in mind just fine. I'll be cutting mostly steel with some 3D surface milling thrown in.

Here's the mill Im looking at: http://www.amadeal.co.uk/acatalog/A...gital-Read-Out-MI_AMA45V_R8M_DRO.html#SID=376

I've been trying to do some research on the steppers needed and control box etc but all the options are frankly blowing my mind.

I like the idea of the Gecko G540 simply because it seems easier to wire up. What do you guys think of this kit, are those steppers going to have enough oomph for this size mill or should I consider 465 oz/in motors for X and Y? http://www.automationtechnologiesin...xis-nema23-381ozin-nema34-906ozin-48v7-3a-psu

Speaking of steppers I read Jumps4's build thread on his RF-45 and raised an eyebrow at the 4200 oz/in he used on the Z axis...that's overkill right? All credit to him though...an awesome conversion I'd be proud to own!

Any help would be appreciated, thanks.
 
Don't know the answer about what size motors for your mill, but the G540 is rated @3.5A and the Nema 34 is more- 5A-6.1A (I think) so you wouldn't be getting the most from your motor. You might want to check out the Leadshine MX4660, or MX3660 rated @60Vdc and 6 amps. Look at the end of this recent thread:
http://hobby-machinist.com/threads/introduction-and-questions.43209/
 
Last edited:
Matabele said:
Hi all,

I'm a complete noob to the world of CNC and was hoping I could get some advice to point me in the right direction. In terms of capability If I could convert a mill to replicate the capabilities of a Tormach 1100 that would suit the projects I have in mind just fine. I'll be cutting mostly steel with some 3D surface milling thrown in.

Here's the mill Im looking at: http://www.amadeal.co.uk/acatalog/A...gital-Read-Out-MI_AMA45V_R8M_DRO.html#SID=376

I've been trying to do some research on the steppers needed and control box etc but all the options are frankly blowing my mind.

I like the idea of the Gecko G540 simply because it seems easier to wire up. What do you guys think of this kit, are those steppers going to have enough oomph for this size mill or should I consider 465 oz/in motors for X and Y? http://www.automationtechnologiesin...xis-nema23-381ozin-nema34-906ozin-48v7-3a-psu

Speaking of steppers I read Jumps4's build thread on his RF-45 and raised an eyebrow at the 4200 oz/in he used on the Z axis...that's overkill right? All credit to him though...an awesome conversion I'd be proud to own!

Any help would be appreciated, thanks.
Click to expand...

There are a lot of smarter people here than me but my setup is similar to jumps4. N42-4200 inoz on the Z and N34-1800 inoz on the X&Y. Each servo has its own combo PS/step driver. Yeah it is over kill but I have never missed a step and can run the mill hard (within limits as it is powerful enough to damage itself). If you drive the head consider it weighs around 300# and the gibs need some tension to keep the head nod to a minimum. If you drive the quill you could use a much smaller servo but it limits your usable travel during ops.

There are several similar builds here and on the CNC Zone that have a lot of good information.

One limitation that was pointed out to me early on and I soon learned after getting the machine running was the spindle speed was too slow for most of the work I do in aluminum and plastics. Some people don't mind but it drove me nuts. I have since converted to a variable speed belt drive / VFD with Mach3 controlling the spindle speed. Some people don't mind but it drove me nuts. If you are mostly cutting steel it probably wont be an issue.
 
I think what you are looking at is for the rf20 size mill. It's about a third the size of the 45. I believe the minimum stepper is 640 for X & Y, 1800 on Z using ballscrews. May even want to belt drive them at 2:1 ratio with that. Go to small you are going to skip steps like crazy. I know someone driving a 6x26 with 465 oz and it would skip steps until he upgraded to ballscrews.
 
Thanks for the replies gents, much appreciated. Some awesome links and suggestions thrown in, I will do some more research it seems I've undersetimated the size of steppers I'll be needing!
 
Jbolt would you mind posting a link to where you sourced your steppers? I've done a quick search but the largest Nema42 I can find easily is 2800 oz/in, would like to investigate a 4200 oz/in for the Z axis. Thanks!
 
Matabele said:
Jbolt would you mind posting a link to where you sourced your steppers? I've done a quick search but the largest Nema42 I can find easily is 2800 oz/in, would like to investigate a 4200 oz/in for the Z axis. Thanks!
Click to expand...

Search eBay using item #181497970139. This is the kit I bought and it is the same one jbolt and jumps4 used in their original builds. The BoB is not the best. I bought one suggested by jumps4 and it has worked just fine. I think I paid $15 for it. I'll see if I can find the item number.

Tom S.
 
Thanks for the link Tom! Are you happy with the drivers in that kit?
 
Matabele said:
Thanks for the link Tom! Are you happy with the drivers in that kit?
Click to expand...

Very happy! Electronics were a new endeavor for me but with help from Jim Dawson, jumps4, jbolt and others I got everything wired and running with just a few minor problems, mostly of my doing. I would not hesitate to buy China made drivers, power supplies or motors.

Here is the link to my conversion. http://www.hobby-machinist.com/threads/taking-the-cnc-plunge.24858/. It may answer some questions for you. You can also do a search on "jumps4" and "jbolt" and look at how they did theirs. We all used the same equipment but made a few alterations to suit our needs.

Hope this helps.

Tom S
 
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