[Kammo1]

Hi I have seen this kit on e-bay http://cgi.ebay.co.uk/3-Axis-CNC-Ste...mdZViewItemand would like to know whether it would be up to the job to power a J-Gro style or Joe style homemade CNC machine. It seems like a good package but I don't want to be chucking money away when it won't hold up to the job, your help and guidance will be much appreciated. Kammo1

[ger21]

You have a bad link there.

[Kammo1]

Maybe this might work http://cgi.ebay.co.uk/3-Axis-CNC-Ste...QQcmdZViewItem

[Oldmanandhistoy]

Buy it now price is good for what you will get but I would like to see more information on the stepper motors. Send a question to the seller asking for the specifications and post them here.

The switch mode power supply would not be my first choice, as I have read many times on the zone that unregulated linear power supplies are recommended. Would be worth your while doing some more research here on that one especially on the Amps rating.

I think Joe uses a 30vdc 2.5Amps/phase rated stepper drive board with very good results, worth looking into and finding out the rating of his stepper motors. Kit rating of stepper motors is 262 oz in so plenty of power for the machines you mentioned.

John

[Kammo1]

Many thanks John for your reply. I will e-mail him and ask about the steppers and see what they say, I just thought it looked like a nice neat package with everything that I need to start the wonderful world of CNC machining, although I will have to build a machine to start with. Very nice to see a fellow countryman from the UK here,what machine do you have and would recommend for the electrics? sometimes you may have to spend a bit more and get a superior product so I probably would hold back and maybe get a package thats better.

[ger21]

It looks like it's based on the same chip that the Xylotex and many others use.

[Oldmanandhistoy]

I have a self built machine (3rd machine) and use drives from http://motioncontrolproducts.co.uk/i...p/cPath/1_8_47 ; the MSD556’s. So far I am very happy with them after nearly two years of use. I know it is not always the case anymore but I still believe in you get what you pay for. Your point about holding back for maybe a better set up is the right thing to do as you can spend a lot of unnecessary money buying and then having to re buy to up grade because you need more power.

You get a two year guarantee with the kit you mentioned and that would give me the confidence to use it. I know there are some driver boards on Ebay that a fellow member of the zone and an EE advised me not to buy but this is not that one.

As ger21 mentioned it is very probably the same chips as the Xylotex; I have a Xylotex board from way back and it preformed very well.

I am sure other UK members will be interested in this so the information on the stepper would be useful. I would like to know also if they sell the steppers separately and for what price as I know finding stepper in the UK at a good price is difficult.

For a first machine or the only machine you build I would recommend the Joe machine over the JGRO but I would look at the other options for rail as this would make building without a CNC to cut parts easier and imo round tube machines are on there way out. If you need any parts or templates CNC cut (so you can use a hand router and a bearing guided cutter to make multiple parts) let me know and I will see if I can help. Can’t guarantee anything because most of the time I am very busy. I would be willing to have one of my employees cut the parts and supply them at cost if that would help. Any way good luck and get building; you will be very happy you did when you cut your first job as it is a very good feeling .

John

[Kammo1]

John the info you and ger21 have said has been very useful and I will take note and not just jump in without checking and double checking first with you guys as I am sure that you have come across snags which if you would of known about first would not have been costly and frustrating which is the stage I am at now. I am itching to build and maybe it would be more feasable to build the CNC first then think about the electronics side of things later, but it seemed like a good thing and maybe it is. I have e-mailed the seller as regarding info on the steppers and will post as soon as I hear anything. I have seen many kits here in the UK and the US which look very good indeed, the snag with ordering from the US is the weight and freight and tax which might cost a bit and also if anything gets damaged theres another headache.
I would like to build a machine with a cutting capacity of lengthways 30 inches side to side 15inches and height 3inches and all it will cut is wood and I hope to use a rotozip or laminate trimmer or something of that nature. There are 2 kits on ebay at the moment which are just what I need a moving gantry design and if these had the dimensions I need they would be on their way to me now, they look great. The Rockliffe machine plans are another contender but they have a moving table design and not a moving gantry or that would have been a good start. It is great to know that there are some good knowledgable people like yourselves who are willing to pass on some sound advice for us noobs so we avoid the pitfalls Cheers!! again.

[Oldmanandhistoy]

I would like to build a machine with a cutting capacity of lengthways 30 inches side to side 15inches and height 3inches and all it will cut is wood and I hope to use a rotozip or laminate trimmer or something of that nature. There are 2 kits on ebay at the moment which are just what I need a moving gantry design and if these had the dimensions I need they would be on their way to me now, they look great. The Rockliffe machine plans are another contender but they have a moving table design and not a moving gantry or that would have been a good start. It is great to know that there are some good knowledgable people like yourselves who are willing to pass on some sound advice for us noobs so we avoid the pitfalls Cheers!! again.

I haven’t been to Ebay for quite some time so not sure what kits you are referring to but I do remember posting to a thread that was discussing Ebay kits. One thing I said and still stand by was that if I were to start again I would buy a kit off of Ebay build it and use it as a learning exercise. I know that one kit provider is said to be very good for email support (kits and bits I think) which would be ideal as I presume he would know what best to use on his machine. Then I would cut the parts for a larger machine using the kit. One of the things that is especially important while self building is accuracy and making my second and third machine was a breeze with a CNC router to cut the parts. After all my parts were cut and I had learned what I could I would sell the machine which would probably if not give me all the money needed, most of it to buy the upgraded parts for the bigger machine.

What ever you decide keep us posted; as you already know there is always some one here willing to help.

John

[Kammo1]

Got the specs for the motors this morning and here they are
1.85 Nm holding torque, 1.8 deg. step angle, 2.0 amp per phase, 4 volts, nema 23 frame size, .25 in. shaft diam.
hope this helps.
I fully understand your theorys as to buying a kit to start with and the more I think about it the more convinced I am that this is the best way to go as for one you know its going to be accurate and when trying to learn all that there is to know about CNC machines and how to even make your first cut the last thing I want is a machine that isn't cutting right and also innacurate. Maybe for now that is what I'll do and get a machine like the kits and bits one on e-bay and maybe build myself another one from this one if I ever need another one. Do you actually make any kits that are available before I contact the seller?? I would sooner go with someone like you as I know its going to be right, not saying that the kit seller isn't going to be.Many thanks.

[Oldmanandhistoy]

Got the specs for the motors this morning and here they are
1.85 Nm holding torque, 1.8 deg. step angle, 2.0 amp per phase, 4 volts, nema 23 frame size, .25 in. shaft diam.
hope this helps.

Only other thing I would like to know about the steppers is how many wires they have. I prefer 8 wire motors myself as this allows alternative methods of wiring them. Bipolar parallel for routers and bipolar series for Mills and lathes. If they are 4 wire motors they will be internally wired as one or the other so I am told, so have to go with what you get. Other than that they sound like good steppers.

I fully understand your theorys as to buying a kit to start with and the more I think about it the more convinced I am that this is the best way to go as for one you know its going to be accurate and when trying to learn all that there is to know about CNC machines and how to even make your first cut the last thing I want is a machine that isn't cutting right and also innacurate. Maybe for now that is what I'll do and get a machine like the kits and bits one on e-bay and maybe build myself another one from this one if I ever need another one. Do you actually make any kits that are available before I contact the seller?? I would sooner go with someone like you as I know its going to be right, not saying that the kit seller isn't going to be.Many thanks.

You had me thinking for a while with your enquiry as I do have spare capacity on my CNC router at present. I would think you would need to sell quite a few kits to recoup costs of design time and prototyping and so on but thank you for the kind words. It would be interesting to know how many people might buy a kit as I am sure there must be a lot of people out there that have the electronics skill but struggle with the mechanical side of the project. Of course once you have the CNC machine it is like having a highly skill man or women working for you with out sick days and pay rise requests.
How would you describe your wood working skills and do you have the appropriate tools to self build without a cnc machine to cut your parts?

I am a wood machinist by trade with too many years of experience as a cabinet maker and bench joiner to boot. The first machine I built took far too long and it would have been far more cost effective to buy a kit and work the hours it took me to build myself doing my normal day job. Don’t let me put you off building your first machine yourself it is just my experience. I must also add I did not know about the cnczone at the time.

What ever you decide keep us posted,

John

[Kammo1]

John have you seen this kit on ebay http://cgi.ebay.co.uk/CNC-ROUTER-ENG...QQcmdZViewItem this is exactly the sort of cnc I would like to build only I want a little more cutting length,width and height. The gallery pics show some cuts this machine has made and they are superb!!!!!!! Could you do a kit like this but with a cutting length 0f X=18 Y=30 and Z=3inches ??
The kit looks like its fairly priced as the guy who has made it must of put alot of time and research into it so has to make his time back can't argue with that. I'm sure if you could do this kit I would consider buying one.
Whilst I was researching making my own homebrew CNC and making a few notes I wondered how you guys made the Z axis and what size to use when you haven't got the spindle. I would like to use a Rotozip or Dremel advantage or a small laminate trimmer and would like it to have a cutting clearance of 3 inches how do I work out what zize to make the Z axis so it has the correct travel to accomplish this. Sorry guys if this sounds daft but without the spindle masurements I don't know what to do and any help would be greatly appreciated.

[Oldmanandhistoy]

Yes I have seen that kit before and that one was the one that was discussed on this very forum a little while ago now. If I remember correctly a couple of buys praised it and the support that came with it.

The first thing to consider while designing your Z axis is not the spindle but making sure that the longest cutter you will use will clear the thickest material you will cut and the shortest cutter you will use will reach the thinnest material you will cut. Then you need to consider the weight of the spindle and the rigidity that you are happy with.

My advice would be to first consider do you have the time and skill to build a machine with out a cnc machine to cut it. If no then buy a kit, if yes then take a look at the JGRO plans and investigate what others have done to improve the design.

John

[Kammo1]

John many thanks on again some sound advice it's all starting to make sense now. My woodworking skills are pretty good and I do have a variety of tools which used correctly should produce a reasonable first time homebrew CNC.
My main stumbling block is trying to work out how its all going to fit together and sizing of the machine which with a further delve into this wonderful site shouldn't present a problem. I will probably start today in making some templates that I can use to rout out the final shapes and see how it will all fit as at least if I do it this way it's not going to be costly later on. Again the kit on e-bay is another option and if all fails on mine I will probably buy this one as looking at the pics it has produced some stunning results.

[mcpltd]

Before you buy any driver kit for a project like this you need to understand exactly what you want to get from the drivers and motors.
If you want a reasonable speed, you need high voltage drivers (Higher that 24V) low inductance motors connected in parallel (This means twice the series current)
The attached image is a torque curve showing two motors with the same holding torque but one rated at a higher current (lower inductance) connected in series and parallel.
As you can see the 4.2A parallel connected motor has three times the running torque than the 1.4A series connected motor at 3500 PPS.

Hope that helps.

[Kammo1]

Well guys I have purchased the CNC package in the link above and although maybe it might not be what you guys would of got it it is going to make my life alot easier as I know everything is compatible and should work together.
Now a question I have is this, how can I check that everything should be working as it should ?? can I do a test without running a CNC software or shall I install some software on my PC and which would be suitable as a trial ?? I would love to see them steppers spin and I know that all is workinf perfectly. My main concern is if I leave it till the machine is built the warranty probably would of expired and I would have some unsuitable parts for the bin, any help would be greatly appreciated. By the way it looks a real nice package and seems well built but the proof is will it work.

[Oldmanandhistoy]

Well guys I have purchased the CNC package in the link above and although maybe it might not be what you guys would of got it it is going to make my life alot easier as I know everything is compatible and should work together.
Now a question I have is this, how can I check that everything should be working as it should ?? can I do a test without running a CNC software or shall I install some software on my PC and which would be suitable as a trial ?? I would love to see them steppers spin and I know that all is workinf perfectly. My main concern is if I leave it till the machine is built the warranty probably would of expired and I would have some unsuitable parts for the bin, any help would be greatly appreciated. By the way it looks a real nice package and seems well built but the proof is will it work.

First point is that the stepper may run rough if run unattached to some kind of load due to rotor inerter.
The only true way to test the set up is to test the system via software. Download Mach 3; it would be a good idea to learn the set up anyway as it will save you some time when it comes to setting up your finished machine. If you get stuck there are plenty of users here who will help you out (not me I use Turbocnc).

John