Circuit Board milling

[shearder]

Hi All

I am contemplating a small CNC router. My primary objective is to have something I can make circuit boards with. I have been looking at stepper motors and I see .9 degrees, 1.8 degrees etc etc etc... i don't have a clue what that should tell me. Yes i know, 0.9 degrees means 400 steps etc etc. I have seen some that are 40 steps - relatively cheap.

What should i get for this sort of work? Let's say i want top spend as little as possible but within considerations for the requirement to make circuit boards. I would also use it to engrave/cut/shape perspex.

[ger21]

1.8 degrees are the standard steppers that everyone uses. You can use the 0.9, but they typically cost more and don't really have any advantage for this application.

[shearder]

Hi ger21

OK that sounds good to me. The next question is, a 48step/7.5 degree stepper is no good for this sort of application i take it?

Oh another question - what should it's torque rating be? I have seen one with this 1.8deg step, hold torque, 2.5W, 40mm dia, 5V, 70mNm - is that worth anything?

[ger21]

Stick to 1.8 degree.

Torque depends on a lot of factors relating to the specific machine your building. How much does it weigh, how are you moving it, how fast do you want to go? Could be anywhere from 100 oz-in to 300 oz in for a small circuit board machine. The motors you mention are probably much too small.

[draughted]

starting to build a machine you might like to look at the types of small routers available
i made a rockcliff fixed gantry it has a 12"*12" work area big enough for any pcb
it uses 260oz in motors and can do most wood cutting i require

i suggest 150 oz in motors from keling industries linked up to a gecko g540

and make a small flying gantry with a dremmel or laminate trimmer like bcackalica has done

[Arquibaldo]

Dear "draughted "

In your previous post you "say":

"make a small flying gantry with a dremmel or laminate trimmer like bcackalica has done"

could you please post a link about this flying gantry? I'm very interest in such a design.

Also, in your thread: http://www.cnczone.com/forums/showthread.php?t=82515 - post #7, your attachment:

http://www.cnczone.com/forums/attach...8&d=1248595637

is a blank pdf page - could you fix this?

Thanks

Nelson

[TOTALLYRC]

Originally Posted by shearder Hi All I am contemplating a small CNC router. My primary objective is to have something I can make circuit boards with. I have been looking at stepper motors and I see .9 degrees, 1.8 degrees etc etc etc... i don't have a clue what that should tell me. Yes i know, 0.9 degrees means 400 steps etc etc. I have seen some that are 40 steps - relatively cheap. What should i get for this sort of work? Let's say i want top spend as little as possible but within considerations for the requirement to make circuit boards. I would also use it to engrave/cut/shape perspex.

There is a lower limit on price and then you are just trying to make it as cheap is possible for the challenge of it.

A gecko G540 and some smaller steppers in the single stack nema 23 size would work well.

I would guess you will be below a 12" x 12" size machine. Most likely 1 -3 inches in the z axis. A cheap machine will be fine for engraving perspex and such but for circuit boards, where the traces can be separated by .005" or less, some rigidity and repeatability are going to be required.

It all comes down to the tolerance that you need to hold.

There will also be a minimum speed that you will need to travel below which you are just gnawing your way through the material instead of cutting.

If you tell us your budget and size and such, we would have a better chance of helping you with this.

As little as possible to make circuit boards could be $500? I think that $1K for the electronics, motors, spindle, and material to build the moving parts of the machine is a much more reasonable number.

Having used an inexpensive driver like Xylotex, I would strongly suggest you save up and get something like the G540, wish I had known the difference when I bought my Taig.

Mike

Mike

[shearder]

Originally Posted by TOTALLYRC There is a lower limit on price and then you are just trying to make it as cheap is possible for the challenge of it.

Yes - that's key - cheap as possible but NOT to sacrifice the quality of the required product - the circuit boards!! "Cheap" because i need it to manufacture parts for my actual hobby

A gecko G540 and some smaller steppers in the single stack nema 23 size would work well.

One of the only places i can find steppers that are worth getting is from a place down the road from me. a motor like this http://za.rs-online.com/web/search/s...duct&R=1918306 - what would that do? I can't find info on their site like NEMA 23, 34 etc etc

I am battling to translate what i see on a seller site to what i need i.e. torque/NEMA number etc etc...

I would guess you will be below a 12" x 12" size machine. Most likely 1 -3 inches in the z axis. A cheap machine will be fine for engraving perspex and such but for circuit boards, where the traces can be separated by .005" or less, some rigidity and repeatability are going to be required.

Absolutely because i noticed, even drilling holes manually with a press, the tolerances are such that you notice very slight alignment changes in the press even though everything is tight - this is noticeable because the drill bit is only 0.6mm-0.8mm and one can see it slightly move when drilling a hole.

It all comes down to the tolerance that you need to hold.

agreed!!

If you tell us your budget and size and such, we would have a better chance of helping you with this.

Electronics i can make myself by etching one or a couple of boards myself. My actual hobby needs 15 boards which are double sided. Quite honestly, if i need to spend $1K i may as well spend $1.5k and buy one off the shelf - R15000 in my currency.

My budget for this is actually $0! And will be "stealing" from the other hobby requirements to build this to make stuff for the other hobby LOL - see where i am heading? So when i say cheap - i need to get precisely what i need only. I have tools to build - i.e. bench saws, routers (manual) compressors, welders mig/mag - arc, etc etc - just NO CNC grrrrr... So i can keep costs down doing 90% myself.

As little as possible to make circuit boards could be $500?

that may do it for me.

I think that $1K for the electronics, motors, spindle, and material to build the moving parts of the machine is a much more reasonable number.

again may as well spend $1.5 and buy off the shelf. My issue is that to get boards made for me is more expensive than I planned. So, yes, i can get it done but i would rather build a small CNC and make boards and have the CNC after rather than pay someone to fill their pockets on something that really is NOT that difficult to do - just time consuming using ferric chloride LOL

Having used an inexpensive driver like Xylotex, I would strongly suggest you save up and get something like the G540, wish I had known the difference when I bought my Taig. Mike Mike

Mike, you have, as have the other guys posting, helped me a seriously great deal. SO possibly I should just buy one? or build one... or just get someone to make boards for me...

Look at the D 40 - http://www.cncmachines.co.za/index.p...d=49&Itemid=34

[shearder]

I was looking at some designs and I was wondering - a fixed gantry or fixed platform? Do you get the same precision with a fixed gantry? I suppose ikt is almost the same?

What are the pros and cons?

[TOTALLYRC]

Originally Posted by shearder Yes - that's key - cheap as possible but NOT to sacrifice the quality of the required product - the circuit boards!! "Cheap" because i need it to manufacture parts for my actual hobby One of the only places i can find steppers that are worth getting is from a place down the road from me. a motor like this http://za.rs-online.com/web/search/s...duct&R=1918306 - what would that do? I can't find info on their site like NEMA 23, 34 etc etc I am battling to translate what i see on a seller site to what i need i.e. torque/NEMA number etc etc... Absolutely because i noticed, even drilling holes manually with a press, the tolerances are such that you notice very slight alignment changes in the press even though everything is tight - this is noticeable because the drill bit is only 0.6mm-0.8mm and one can see it slightly move when drilling a hole. agreed!! Electronics i can make myself by etching one or a couple of boards myself. My actual hobby needs 15 boards which are double sided. Quite honestly, if i need to spend $1K i may as well spend $1.5k and buy one off the shelf - R15000 in my currency. My budget for this is actually $0! And will be "stealing" from the other hobby requirements to build this to make stuff for the other hobby LOL - see where i am heading? So when i say cheap - i need to get precisely what i need only. I have tools to build - i.e. bench saws, routers (manual) compressors, welders mig/mag - arc, etc etc - just NO CNC grrrrr... So i can keep costs down doing 90% myself. that may do it for me. again may as well spend $1.5 and buy off the shelf. My issue is that to get boards made for me is more expensive than I planned. So, yes, i can get it done but i would rather build a small CNC and make boards and have the CNC after rather than pay someone to fill their pockets on something that really is NOT that difficult to do - just time consuming using ferric chloride LOL Mike, you have, as have the other guys posting, helped me a seriously great deal. SO possibly I should just buy one? or build one... or just get someone to make boards for me... Look at the D 40 - http://www.cncmachines.co.za/index.p...d=49&Itemid=34

The D40 looks like a nice enough machine.
If the budget is really tight, and yours looks like it is very tight, you can go with a Xylotex driver or maybe a hobby CNC kit since you seem to be able to handle the assembly.

Don't go with round steppers since they "may" have suffered partial demagnetization due to their age.

This is a nema 23 motor.

http://docs-europe.electrocomponents...6b8001c796.pdf

The nema 23 really refers to the bolt pattern and overall size. They are available in different "stack" lengths, 1, 2, and 3 being the most common.

For a dedicated machine that will only do a 6 x 6 part you might be able to use a nema 17 motor since the cutting load for doing PCBs is not much but I am not 100% sure since I have not cut any PCBs, yet.

I didn't realize that you were in South Africa, I take it for granted what you can buy surplus in the USA and the prices can be really cheap sometimes too.

When you get either single stack nema 23 or nema 17 size motors the cost really drops. Most people thank that you need monster motors to do the job but all you want to get is the smallest motor that will do the job, it makes it much more efficient.

I guess if you can find the motion components cheap, the the cost will be reasonable.

Mike

[eSilviu]

Originally Posted by shearder Hi All I am contemplating a small CNC router. My primary objective is to have something I can make circuit boards with. I have been looking at stepper motors and I see .9 degrees, 1.8 degrees etc etc etc... i don't have a clue what that should tell me. Yes i know, 0.9 degrees means 400 steps etc etc. I have seen some that are 40 steps - relatively cheap. What should i get for this sort of work? Let's say i want top spend as little as possible but within considerations for the requirement to make circuit boards. I would also use it to engrave/cut/shape perspex.

look what I've user for pst 2 years:
http://www.cnczone.com/forums/showthread.php?t=42554

for PCB only, It should be smaller, and many of the problems enumerated there should not exist at all.

[shearder]

HI all

Mike GREAT info - thanks - and yes, unfortunately being in SA the companies (company owners) are more interested in overpricing all good because it is a race as to who can drive a bigger car. Unfortunatey it is what they use to define themselves so the idea of getting anything as surplus is near impossible. However, perhaps i can find a company that will reasonable ship to South Africa though i have seen shipping of $20 on a 0.99c item. So basically, with shipping and weights calculated i may as well buy it here.

eSilviu - GREAT looking machine. This is all i want. When you say you used a driller - you mean a simple tool that one would use to drill holes into wood, walls etc? If so, is the RPM sufficient? That is EXACTLY what i am looking for!! DO you have the plans? Or where could i get simple plans like this. I seenow what drilling machine you are usinig - are these (like Dremel) good enough for the job? would it not wear the bearings out on them?