New build - Screw specification???

[HiltonSteve]

Hi all,

I have a couple of questions for you.....

1- The machine I am looking at building is a router with a travel distance of approx 600mm on the X axis and 500mm on the Y. I would like it to be quite accurate so what do you suggest, ball screw or something else and what size?? Also what would be a good travel distance for the Z?

2- Looking at using the mach3 software to run it but do i need a specific pitch screw and a specific stepper motor or is it configurable in the software? Had a look but can't see any obvious way of adjusting it.

These may seem like dumb questions to some of you but this is my first machine build and everything is pretty new to me, just trying to save myself some money and time by listening to other peoples experiences.

Thanks.

[Lee Roberts]

Yea like Kip said, in mach3 you have the options to setup and make the adjustments you need to. Once your machine is up and running, you then go in and fine tune everything as you need to.

I'm also designing a Z axis at the moment, I will be looking to get around 100mm travel on that axis, I think the thing to look at would be the purpose of the machine, what you would be likely to cut with it and then base things around that.

My machine is going to be for very light work really, predominately cutting through 3mm ply, over a distance of about 4'x2'. So I want a machine that will be accurate, strong and at the same time have quite a good cutting speed so it keeps everything viable over having the parts cut on something like a laser machine.

As such my z axis doesn’t really need allot of travel but dose need to be well made and ideally using supported linear rails.

Hope this helps you in some way.

[Smiler]

Hi all,

I have a couple of questions for you.....

1- The machine I am looking at building is a router with a travel distance of approx 600mm on the X axis and 500mm on the Y. I would like it to be quite accurate so what do you suggest, ball screw or something else and what size?? Also what would be a good travel distance for the Z?

2- Looking at using the mach3 software to run it but do i need a specific pitch screw and a specific stepper motor or is it configurable in the software? Had a look but can't see any obvious way of adjusting it.

These may seem like dumb questions to some of you but this is my first machine build and everything is pretty new to me, just trying to save myself some money and time by listening to other peoples experiences.

Thanks.

1. Don't think you can beat ballscrew for accuracy with trapezoidal screws a good cheaper alternative. I use rack and pinion on my Y axis (longest) and it works very well indeed, also gives me the option of easily extending the Y axis should I need to.

My Z axis has approx 145mm BUT when making the Zaxis plate (the static one that rides on the Y rails), I made it so that I can raise it another 100mm by moving the whole assembly up. It doesn't change the Z range but it does allow me to put extra thick material on the machine and gives a good height to fit a rotary 4th axis, so PLAN AHEAD, it took 10 minutes to drill the extra holes.

2, as the others have said, Mach will work with any screw, belt,rack, motor. You just need to tell it how many steps per unit (mm or inch) and it works the rest out. Just ask when you come to this bit and someone will fill you in on how to work out your steps per unit.

What do you plan on making with the router as that can have quite a bearing on how you spec your hardware.

Welcome to the forum BTW

Jeff.

[HiltonSteve]

First of all I would to say thanks for some very good answers to my questions, this was what I was hoping to get and it looks like I am in the right place. You can tell straight away when people are pretending to know the answers and when people actually know the answers!

So what I am now thinking of using is the following, please bear in mind that this is my first build and I am still open to suggestions...

1- I will be using the driver kit 1 on the Zapp automation website - http://www.slidesandballscrews.com/c...e9ad8184c36c4c

2 - Drive screws - I will be using 16mm ball screws, not sure where from yet but if anyone has any or can recommend a supplier then let me know.

3 - Linear guides / slides - Open linear bush's with fully supported rails on X and Y - probably 16mm - again not sure of best source/supplier. Z axis, going for 200mm travel to allow for milling cutters and drill length variances with mechanical adjustment for larger workpieces (good idea jeff)!

4 - Custom designed frame made from aluminium plate, found local supplier with very good prices for material.

5 - Spindle - not sure yet, maybe looking at a Dewalt or Metabo electric die grinder.

6 - Software - Mach3 looks like a good package, downloaded the evaluation version and had a play with it last night with some good quick results.

Once I have decided on the mechanics then I will start the design process which I will be happy to share with everyone that has helped and even the ones who have not but are interested.

Everything will be drawn up in my 3D cad package (Solid Edge) and i will post my designs on here for evaluation and criticism! I know my machine will not be right first time (is anything) but I am hoping with your help that I can get it pretty close to something that I will be happy with.

Thanks so far to Kip, Lee and Jeff (smiler). Without your input I would have probably given up before i got out of the starting blocks....!!!

Oh yes, did I say I was in what looks like the CNC capital of England.....Derby!

[BillTodd]

6 - Software - Mach3 looks like a good package, downloaded the evaluation version and had a play with it last night with some good quick results.

Don't over look EMC2 (linux based and free)
Don't be put-off by Linux either, the complete Ubuntu+EMC install is pain free.

[BillTodd]

Mach software is brilliant!

Hmm, last time I had a close look it looked positively unfinished compared to EMC (will have to look again)

[HiltonSteve]

Hmm, last time I had a close look it looked positively unfinished compared to EMC (will have to look again)

Must agree with you to a certain extent, it does look like they have not finished it off but it is very functional, just a bit tatty round the edges if you know what i mean!

[Lee Roberts]

Steve your more then welcome mate, dont worry about your spindle just yet mate get everything else sorted out first. Like me you will pick up information and knowledge as you go. Also if you have a look on zapp's website you can get the ballscrews and 16mm rail all under one roof.

Kip its not my spindle, it was by cncdudz. My design was always 43mm ! Do you have a good source for the 20mm supported rail ?

[michael]

Hi HiltonSteve,

Thought I was the only hobbiest CNC bloke in Derby! I have built a few machines and currently use my largest for profiling/machining 10mm Aluminium. I changed the design several times mostly the Z axis as I need it to be as rigid as hell.

I used 20mm fully supported rail (THK) similar to the Hiwin rail it has a key shaped profile. It can take massive loads.

I used 10mm od ball screw with a 3mm pitch which with my 23 frame motors gives me a max speed of about 2000mm per min (not that fast but fast enough for a machine 600mm x 300mm).

Your welcome to have a look if it would be of any help as your nice and local. I could also point out where I went wong! I also have a small lathe so could turn down your screws if needed.

Something else to consider (depending on the accuracy you need) would be Trapezoidal leed screw. I use this on another machine and made my own nuts out of both delrin and PTFE, Its good to approx 0.05mm. It is also very cheap, 10x2mm is 80p per 100mm and I already have a Tap to make nuts.

Mike.

[John S]

Must agree with you to a certain extent, it does look like they have not finished it off but it is very functional, just a bit tatty round the edges if you know what i mean!

Can be tidied up by the user if needed, there is a screen designer on the support page. I have altered our copy so that everything including setting up tool offsets etc is all on the first page and dropped a load of the non needed stuff.

I also took a recent look at EMC2 again but gave up, not saying it's no good but unless you are a Linux techie it's very, very hard work.
Basically it's written by techies for techies and not machinists.

Break a tool, need to jog clear, fit new tool and reset length then carry on ?

No can do, bail out and start again.

John S.