Thread: help needed 8' x4' cnc

P.S As Chris noted, there are plans for the mechmate and they are well documented. They are also easily changed to suit avaliable materials and upgrades to make parts better etc, thus making it a great machine to build and upgrade as your needs grow.

Hi Daniel and Chris
Thanks for the info

Now since that original post where I was looking into getting the combo (which would be ideal I guess... ) what Daniel indicated as a price definitely cooled me down...
I had an oportunity to swing past linearbearings shop (Home) on my slightly derailed work related trip
Sales rep gave me following prices for their economy range
HER20 Rail is $110 per metre and they can do them up to 4 metres lengths
HEW20CC Bearings are $66 each...

Queried him about supported round tube linear bearings package.. and was told that it is about two to three times more expensive than economy linear bearings
Apparently when standard linear bearings came out they were extremely expensive so the tube ones were cheaper option at that time.. But since economy range came out ... economy is comming out as the cheapest option
I have also asked about the rack and pinion, and was told that they have very limited range (and too big for my needs) and was refered to go to ronsongears for rack and pinion... Now I'm just trying to find another excuse so I can go for a visit..

I might also pay hommandesigns a visit and pick their brain too.. hope they wouldnt mind...
)
Now I don't mind spending bit extra on the G540 kit and add extra motor.. (they do sell the same G540 with 4 387 steppers) but how do you connect them??
Can a single controller drive both motors (connected parallel) or ...
perhaps to rephrase question
How do I run two steppers in sync?????

Ohh soo many questions and I haven't event touched the "spindle" topic.. and yes I am reading and searching around. .but at this stage the more I research, more questions I have and more confused I get.. so I am hoping to get as much info info from you guys as possible.. (without trolling the forum)

EDIT: As a reply to twistedfuse.. As much as I like mechmate designs, unfortunately I would need to make something that can be taken apart (at least partially) since I'm renting this house moving will definitelly happen.. Once I build my own place (hoping to do that within 12 - 24 months) I might give it a go with mechmate design (depending how this design go)
Mechmate are very solid (I love the design) but I need something I would be able to move out without having to rent a crane

Yes I agree that linear rail is the best you can use, but for us cost and design of the machine was an issue. I didn't have the time to retro the design and by sticking to to Mechmate plans it made the build easier and cheaper $220 for the bearings and $100 for the steel used to make the rails Also the laser cut kit for it would have needed changing adding more costs. As we progress with the Mechmate its something we haven't excluded upgrading to linear rail but at this stage the v-rail works fine. The original designer of the Mechmate I think was running 7 of them in his sons cabinet shop with very little issues with them.

Hi,

The sales rep at linear bearings is correct and sounds down to earth. When i first got into cnc about 10 years back, round bearings ruled as the costs were almost 1/3rd of the price of profile rails and bearings. Theses days with cnc getting more and more popular the price and need for profile bearings/rails is dropping rapidly. As you can see, they are not overly expensive anymore although still a bit more. Alot of hobbyists are mislead by the fact that the round rails are in abundance on ebay and such, thus think it is the better option cost wise as it must be a deal as its on ebay.

When it comes to the economy range, take note of the different features between them and how you will use them. I have seen some economy rails and bearings with 2 rows per side of rail for the same as rails with only 1 per side. Difference being that the 4 row bearings are made for equal distribution and can be used without worry on all orientations, where some 2 row bearings will struggle on their side and wear quickly...something that you don't want as its still a fair price to pay. Just keep and eye out and also check some of the low end of their precision ranges as some like Hiwin, THK etc have some reasonable prices which may see an extra outlay of say ~100 for the lot you need but you'll get a better product. Just food for thought.

As for rack, i wouldn't know about ronson gears, but TEA prices aren't bad and will cut to length and deliver at reasonable prices.

Single G540 will easily handle the 4 motors, it will just lower the I/O signals for other things like switches etc, but not by much. recently built a 8x4 plasma with that exact package of 4 steppers so easily doable. The steppers are actually slaved using mach3 control software so it helps. Although there are ways to parallel them but not really needed for the hobbyist.

As for transportability... the mechmate design can be made as a bolt together system which has been used before by a couple of those projects on mechmate to aide in transport for people. Bolt together systems are also very good as it eliminates some welding which means, less metal shrinkage with the welds and bolting allows small amounts of adjustments...perfect for most of us who cannot afford/own/use large stress relief kilns and bridge cnc machines to get perfect frames and mounting surfaces. lol.

Keep us in the loop and ask many questions/clarifications on anything your researching and i am sure many here will be willing to help. Just don't sit up too late at night browsing and reading those forums...lol.

Daniel

Thanks Daniel

Spoken to one of my suppliers regarding the steel...
picked his brain about 100x100 square mild steel tubing.. Was told (pretty much confirmed what has been told on forum) that they are not 100% flat...
Now in saying that he told me he has an I beam table 3mtrs long not sure whats the width which he got on auction few years back.. table is machined flat.. apparently it was used as a flat surface to make other flat / level tables
Was invited to have a look.. now if I can transport that properly (or get him to sort of chop it in pieces which could be bolted together leaving level I beams I might get myself a table.. !!!!
All I have to worry then is mounting the gantry... hmmm
need another work related trip..
Hopefully monday.. will see to take photos and will post them and see what you guys think..

Look forward to seeing some pictures as it would be interesting to see the table. Sounds like a surface table for welding or jigging but would have to see the pictures.

Consider and try to come to a decision on what you will end up using for your linear motion before going too far into the frame build too. I have seen a few builds where people buy expensive materials, machine the surfaces for bearings(expensive) then use round linear rails etc, which IMHO, is close to pointless and waste of cash depending on use. Also think through what you really want/need from the machine. As you could worry yourself sick about how accurate pieces are etc for something that might not be applicable for your machine due to needs. Been there and done that and it takes the fun out of the build and can frustrate you to the point where you might not finish.

Remember there are easier ways of eliminating the need for surfacing like shimming out rails or mounting on epoxy beds thus small discrepancies for a hobby machine might not be a problem when compared to if you were building one to machine injection dies etc. Although i am a firm believer of pushing the budget to get something more first time round, which saves spending the same amount by having to rebuild numerous parts or build a new machine later, which, when you get hooked, i am sure will happen and personally do not see the point in building a wooden cnc(nothing wrong with it, just personal opinion here), except suiting someone with a strict budget, i believe they are great to show you that you can get great results from inaccurate parts etc.

All in all, when it comes to it, anyone building a cnc should try to be as honest with themselves and set a realistic project list(needs vs wants, budgets, final use etc etc etc) as we always want more. By reaching for the stars we can have some amazing leaps forward but by reaching too far beyond our limits we can stifle ourselves and loose interest, something i hate to see in any hobby, as it is so rewarding to finish.

Anyway, enough dribble for everyone. Keep up the great work, you seem to be on the right track.

at about this stage , after the first round of pricing , and head scratching , some one should point him in " Happyloves " ebay sales direction ,
yes small , yes controllers dont work , yes couriers will wreck at least one part because of weight
but , they are decent , at a dam good price , with 1/100th of the head scratching

t, bolt bed
average quality round supported guide rails and guide blocks
16mm diameter 5mm pitch ball screws
spindle fitted
you can do way worse for the price he's asking ( $2000)

Hi guys
thanks for suggestions..
Well I'm 90% sure I will go down the way of economy linear bearings rather than round shaft ones...
reasons..
well from what the linearbearings guy told me .. the round shaft ones will be more expensive than the economy range
additionally I think that the economy range would be easier to mount / shim / maintain..
they look nice..

Now ....
I was just informed late last night by SWMBO that I am to take monday off and to prepare for a weekend trip to adelaide.. so my monday visit to the steel guy will be postponed for tuesday...
I am also very interested to see that table and yes you're right .. we believe it was used for jigs and leveling.. so I believe it has to be fairly straight,,
hopefully I might be able to do something with it as that will be major cost saving on material and everything (might be able to get it for couple of hundreds and perhaps slab of beer... which is a native currency for suppliers and tradies )
Once I see the table (and check with you guys) might proceed to further planing...
Still have to see the rack and pinion
also the steel guy has access to the laser cutter so might be able to cut few pieces if needed (but it will cost me though)

The whole idea is to make table as versatile as possible.. (trying to milk the money invested as much as I can)
Generaly most of the time it will be cutting plywood pieces
I might attempt to do some work on hardwood but not fussed..
Bonus thing would be if I would be able to mount dremel tool so it can work on PCB boards or nice engravings...
(I am planing to have Z axis tool holder switchable.. or at least adjustable to different tools)
Had a bit of investigation regarding spindles.. and got myself confused.. yes... I am spending late hours reading all of the info I could get and most likely everything became blur after 1:00 am so might need to read again..
Still trying to figure which spindle to use.. water cooled, air cooled.. do I need VFD or not?? soo many questions..
Also with spindle.. would I be able to put standard 1/4" router bit or it is not really recommended..

the spindle will come with a changeable collet , ?/ ER11 , will take anything from 0.5mm to 8mm , if you bye the different sized collet's
yes you can put an engraving bit in them , just dont run the machine as fast ( you will snap them )

yes you will need a VDF to power your spindle ( designed to run at 400hz 3 phase )

you can get collet's to fit your makita , so that it will take dremmel bits

Here is another site for you to check out....This is where I purchased my spindle and VFD.

Cheers,
Kym

DamenCNC.com - ElectroSpindle

Not sure about the round rails being dearer but the difference is minimal. Investing in the economy range will bring a little more rigidity and well worth the price. I agree too, makes the final look a little more professional too.

Beer...ah yes the Australian equivalent to money. Also access to a laser cutter will be a big advantage in some cases, try to find a manual machinist or access to a mill is probably a huge advantage too.

Checkout the TEA website to see the rack and spur gears in their catalog pages. Also check out their economy range of linear rails. Might be able to pick everything up at the one place.

Not putting you off but just food for though, if you dont have any major need for a 8x4 maybe think about a half sheet router 4x4 as you will find it will cut costs alot and parts are a little more accessible. Also being able to move it around/transport would be a lot easier. You can still cut parts longer than the machine by indexing the sheet, but it all depends on how much you think you would cut of the full length sheet.

Spindle wise, the air cooled spindles are easier to setup as there is no need to run coolant pipes and setup a pump etc like the water cooled ones, but my opinion would be, if possible, to get a spindle that has an ER20 collet. This is because it is the first collet range capable of housing a half inch router bit. This expands the capabilities of the spindle to having some hefty and specialty router bits but is not a huge requirement. Other than that, as described above, the ER11 would be the first. And yes a VFD is required as it converts the single phase power to 3-phase power which the VFD controls the frequency to create the different speed ranges.

Daniel

Thanks guys
Will proceed with further investigation on tuesday as i dont have access to the pc at the moment and browsing on the mobile is really crap

HI, Mabey our rack and pinion may interest you? CNC AND CUPCAKE WORLD items - Get great deals on items on eBay Stores! If you want to come and have a look, just send a message thru ebay. We are in Clayton.

Hi guys
here is a link to a CNC kit available here in Australia that sounds like what you wanna do. He has a free forum that you can join and download the plans. The site is www.squarefootcnc.com.au
cheers