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-   -   Build a functional MechMate at lowest cost - what can be done cheaper? (http://www.mechmate.com/forums/showthread.php?t=1174)

WTI Wed 03 December 2008 13:23

Also, those big, tower computer cases make for a cheap metal box to put all the MM electronics in.

Look for the Dell server cases with the hinged side panels - they usually have Xenon 2 processors that run at 450mhz. It seems that businesses can't GIVE these things away, as I see them come up in groups of 5-10 at a time.

http://www.mironet.cz/fotoadd/92401417.jpg

The blue paint awaits....

domino11 Wed 03 December 2008 13:33

James,
Can you run xp on those machines? Never tried running xp or vista on a server board before. :)

Gerald D Wed 03 December 2008 13:48

We run Mach on Win2000 - it is much easier to move from one machine to the next

domino11 Wed 03 December 2008 14:00

No I meant on server motherboards with Xenon processors. They are different than standard pc motherboards. :)

Talons Wed 03 December 2008 16:06

w2k and xp will run on any mobo with even a 233mhz cpu but boot time is real slow 350mhz or higher work great only drawback i find with 233mhz upto 1ghz is hhds most older mobos only see 8gig hdds or smaller hope this helps

Talons Wed 03 December 2008 16:22

The questions i have is lasercut Nobody here has it but i have a friend who does waterjet and it's just as precise and cheap for me here. and is there a problem if some of the gantry and router base mount parts are aluminum? i have both steel and aluminum i'm just thinking of overall weight. btw thanks :)

Gerald D Wed 03 December 2008 20:56

Thanks for the mobo info Talons.

Alu will not save costs (the topic of this thread). We are not desperately on a mission to save weight because weight does more good than harm. The best CNC routers are built heavy and use little alu.

WTI Thu 04 December 2008 02:09

You can get a free, heavy duty transformer for your power supply out of any large microwave oven. These are also free on craigslist every day.

Most broken microwaves fail because the door switches wear out, so the MW blows the safety fuse instantly.

If you take the transformer out and cut off the high voltage windings with a hacksaw, you can quickly wind a few wraps of wire until you get the voltage you need. It is usually about 1v per turn of wire. Don't forget that you want a secondary winding for about 9-12V to power your BOB.

Just Google "microwave transformer power supply" for many easy to follow directions.


EDIT: Don't touch the high voltage capacitor if you take a MW apart. It will still have juice in it unless it has a bleeder resistor.

Gerald D Thu 04 December 2008 02:18

James, that hack makes me nervous! If anyone wants to pursue this for a MM, I'll give you a thread where you can field the lawyers all by yourself! :D

James started his own thread and I copied the above posts over there.

javeria Thu 04 December 2008 09:52

OK folks - on cable chains - if the ready made ones are expensive then you can make your own on your Mechmate

http://www.cnczone.com/forums/showth...=25257&page=10

look at this thread and there will be no heading back for you - I am going to do it this way for sure :)

normand blais Sat 06 December 2008 11:07

1 Attachment(s)
Here something I had though doing ,not to save money but be practical,in that case . I was doing some cuts for movie at some studios ,my idea was to build 2 concrete curbs and put some spare rails on it to ride the gantry. Screw the first ply to the concrete floor then glue the sacrificial board on it .
When not in use I could easily take the gantry home or some other place by myself in a small van .

Doug_Ford Sun 07 December 2008 19:29

I would have saved a lot of money if I had read the plans carefully and made a list of all the fasteners (bolts and nuts) that I needed and placed one order from Enco or MSC rather than running down to Lowes or Ace Hardware and paying full retail price.

gmessler Sun 07 December 2008 21:17

I'll back you up on that one Doug!:)

Greg J Sun 07 December 2008 21:43

I think Doug makes one of the best cost savings suggestions so far.

If I was better at project planning, I would have saved numerous hours and cut costs substantially.

Take your time men (only because no women are building so far), and document your plan to the end. Easier said than done. :)

dragonfinder1 Tue 09 December 2008 18:15

In the first post of this thread there is a link to homeshopcnc which has a motor RS23-570 which is a 420 in oz holding torque motor ( uni polar). I know this is a nema 23 motor and it is small, but I plan to use a 3:1 belt drive, so the torque will be over 1000 in oz. Might this motor work with the belt drive?

Dave

MetalHead Tue 09 December 2008 20:16

Motor Mixing
 
Why would you need the PK296A2A-SG7.2 for the Z Axis?

Why not use a cheaper Motion King for the Z or one of the NEMA34 Motors?

Or have I missed something that says they all need to be the same motor? All the threads I see say the Direct drives are working and for some savings you could use the MK for Z and SG7.2 to drive X and Y.

Gerald D Tue 09 December 2008 22:59

Dave, the smaller motor with a belt reduction could work, but I don't see it making the system much cheaper. Plus there is the risk that it might not work. Can the small motor handle the belt load? How is that motor's torque at working speeds? (Small motor torques at working speeds are generally good compared to bigger motors - overlay some graphs for fun).

MetalHead, if you mix motors, you make fault-finding difficult. Out here, we stock a spare motor. It just makes our life easier if all the motors, drives and power supply voltages are the same. The other thing to consider is that the high detent torque of the gearbox helps to keep the z-slide from dropping when the power is switched off.

MetalHead Tue 09 December 2008 23:35

Motors
 
Makes sense. Did not think about spares.

dragonfinder1 Wed 10 December 2008 15:27

Gerald I think the savings would be substantial IF these motors would work.

OM motors $250 each = $1000
BOB $100
Power supply $140
Drives $130 ea $520
Total $1760

MK motors With shipping $550
Drive G-540 $300
Power supply $140
Belt reducers $140
Total $1130

RS23-570 w/shipping $325
Drive G-540 $300
Power supply (less than) $140
Belt reducers $140
Total $905

True the motors might not take the side loading of the belt drive, but I’m working on that. I have a design that would only add about 50mm to the motor length, so there would be no side loading on the motor at all.

So IF these motors would work, there would be quite a savings for me, I have a machine shop available to me to build the belt drive reducers and the coupling device (if needed).

Is it worth the $350 or so gamble? On paper it would seem so. Will I try it? I’m not sure yet, the RS23-570 motors are pretty small. On the other hand, they are the same length as the MK motors, just the cross section is MUCH smaller.

Dave

gmessler Thu 11 December 2008 00:57

Another cost savings would be using silicone to attach the racks to the rails instead of the VHB tape. $3 tube of caulk vs $45+ roll of tape

Gerald D Thu 11 December 2008 03:42

Greg, that could work. Will need a good long curing time because of the 2 metal surfaces.

shaper Thu 18 December 2008 00:52

MK motors and G540
 
Been lurking for a while now and considering the G540 as a driver largely because it's a bit more straight forward from the electronics side. Which MK motors are you considering for use with the G540, I haven't found one yet that appears to fit the requirements of the G540, keep ending up back at the OM PK296A2A-SG7.2 which I'd like to get away from as to purchase them here (Australia) your talking almost AUS$3500 or trying to import from US which I can't imagine being a lot cheaper.

Jed

dragonfinder1 Thu 18 December 2008 20:07

Quote:
Originally Posted by shaper View Post
Been lurking for a while now and considering the G540 as a driver largely because it's a bit more straight forward from the electronics side. Which MK motors are you considering for use with the G540, I haven't found one yet that appears to fit the requirements of the G540, keep ending up back at the OM PK296A2A-SG7.2 which I'd like to get away from as to purchase them here (Australia) your talking almost AUS$3500 or trying to import from US which I can't imagine being a lot cheaper.

Jed
The MK motor that I would use if I were going to go with the Motion King motors would be the 34HS9801.

When I contacted Gecko Drives, they told me to add a 3.5K resistor for the current set resistor. They calculated that that would give about 87% of rated torque.

If you decided to use this motor, or any nema 34 motor, you should contact them directly to verify the figures, before you buy a drive. Also you have to remember that with the G-540 drive, you don't get the option of an indexer.

Which ever motor I use, I will use a 3:1 belt drive. We're working on a design that will allow me to change a broken belt in about 5 minutes. Even at 87% torque, I would have more than enough power to suit my needs.

Dave

shaper Thu 18 December 2008 20:22

Dave

thanks, will contact Gecko for more info, just on the face of it the 34HS9801 didn't appear to match the info in the 540 manual:(, but if they say it works I'll take their word for it:D.

I don't need an indexer anyway I'm looking at building a heavily modified mechmate for cutting surfboards and occasionally some ply or mdf sheet. Was figuring that the G540 was a good place to start and relatively cheap if I wanted to get more complicated down the track then I can build new control box with G20x drivers.

Not sure about the quality of the MK gearboxes but they tell me I can get 5:1 or 10:1 for $120 with the motor still asking questions about that.

Thanks again
Jed

dragonfinder1 Thu 18 December 2008 20:45

Jed

Here is a link to a very good thread on motors and power supplys ( I hope )

http://www.mechmate.com/forums/showthread.php?t=932

Also the math that I used for the 3HS9801.

Dave

Mike94531 Sat 04 April 2009 01:14

sorry for bumping such an old thread....had a crazy idea while sitting in traffic today....

if you don't mind leaning over near the floor and have nice concrete slab, use concrete machine screw anchors, up to 5K lb pull out rating, more if using a better contrete

http://www.confast.com/products/tech...ew-anchor.aspx

reason I was looking into these was that I've been thinking about my lack of space, so if made a basic frame that I can bolt and unbolt to the floor, I can move the frame for the few times a month I see myself using it...when not in use, I can park my car in the garage where it belongs

Gerald D Sat 04 April 2009 05:38

Hey, in this forum we don't have old threads, unless they are locked in the Archive, and it is much preferred to post in topical threads rather than start all over again. If a thread is not locked, that's an invitation to post - absolutely no need for apologising. :)

inventall Sat 04 April 2009 11:50

some things I did to save $$

My control box was from Digi-key 377-1580-ND only 15.75X15.75X7.87" it is a little small but cost $86 and was ordering from them anyway.

Found a great steel place in Reno NV (Proto- Fab) that would sell me any length at good prices. The 1.5" square by 9 inch long solid bar that I used for the ribs cut on 45's on both sides cost me $4 a piece. That allowed me to use a lot less steel under the table.

I ordered most of the bolts from McMaster carr and Bolt depot.

I used the G540 With the pk296a2a-sg7.2 motors. I will worrier about the indexer later, if ever. The G540 got me up and cutting fast and cheap.

I used Cable chains with cheep foil shielded wire, 250ft for $80 off ebay. My thought is that it really did not need the braiding because it is not really rubbing on any thing. Anyway I have plenty extra. and we will see how long it lasts.

I used Cold-rolled steel for the Z-slide plate instead of tool steel. 1/4"x4"x36" was $24 instead of $150.

I used household light switches for E-stop buttons. and a $6 numerical pad for my bump remote, Works Great.

I did not use a machine shop at all. Only tools i have there are a Hobart mini mig, A drill press, 14" abrasive cut off saw, 4" grinder, and a 3/8 Dewalt drill.

I bought the router re-manufactured as well.

And no paint. Yet.

robb.greathouse@gmail.com Wed 22 April 2009 16:11

What does it cost to be up and cutting in the US? Any rough ideas on budget?

domino11 Wed 22 April 2009 19:47

Robb,
It depends on what you have already, what you buy new and what you get deals on, as well as the options you choose. I know several have built in the $4500 to $8000 range.

here is one guy

Quote:
Originally Posted by smreish View Post
...I built my 5x10 machine with 3HP router for 5819.00 - give or take a few hundred in receipts I probably lost along the way.
You can look at his build log here

http://www.mechmate.com/forums/showthread.php?t=460


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