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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)

Gerald D Sun 30 November 2008 05:43

Build a functional MechMate at lowest cost - what can be done cheaper?
 
How can one build a functional MM that could start earning funds for "upgrading" it later? What is the minimum needed to get it producing sawdust?

1. Stay with the laser cut parts. You could bandsaw/jigsaw & drill those parts if really desperate, but you would spend a lot of time getting everything lined up. It would be a false economy to try plasma cutting instead of laser.

2. Make the rails as per the "grind angle iron down" method. Go gentle on your grinder unless you have a decent brand with a powerful motor.

3. The V-wheels at under $15 a piece from Superior Bearing is good if you live in the US. Make your own mild steel wheels if shipping costs from Superior Bearing are too much.

4. Talking of shipping/transport costs, see if you can consolidate stuff into fewer shipments. Share with a friend.

5. Use direct drive motors with the pinion gears direct on the motor shafts. Motionking ships worldwide. You can get a motor and geckodrive for $209 as a package from www.homeshopcnc.com.

6. The "sexy" Gecko 203V's are not essential. G201's work as well.

7. Don't fit any pushbuttons or limit switches. Apart from the saving on switches, housings and cable, you won't have the concerns of interference entering the electronics on that circuit.

8. Use cheap unscreened cable for everything except signal cables. Separate power and signal cables by more than 100mm [4"].

9. Don't use cable chains. Hang the cables from the ceiling.

10. Use a cheap router.

11. Don't bother with a control box. But do put in ground fault protection if you are going to have open wiring.

12. Stay with domestic voltages

13. Use recycled steel wherever possible.

14. Consider a wooden table with the steel rails screwed on top.

Any other ideas?

Fronzel Sun 30 November 2008 14:09

What about swapping the Break Out Board and the Gecko 203's for the Gecko 540?

isladelobos Sun 30 November 2008 16:34

ideas = 1999 but no thanks. We make a mechmate.

Gerald D Sun 30 November 2008 20:10

Fronzel, that can help too. Your motor selection must be more careful to match the G540.

Lex Mon 01 December 2008 03:57

What about the 'over' existing work bench design as mentioned somewhere before by Gerald.
If one uses the y-gantry and z- axis as is - make up two short rails support structures from the wall cantilever out. The y-gantry will become the x-gantry.
Starting the business of with sign cutting!

Gerald D Mon 01 December 2008 04:42

Yes Johan, that huge solid table is not essential to get going. Wooden longtudinals on an existing table, with the x-rails on top of that, will get you going. (The first ShopBots were on DIY wood tables)

J.R. Hatcher Mon 01 December 2008 05:51

Before I found the MechMate site, I was considering using a product for the main beams and the cross supports called "microlams". It looks like it's made by gluing up a lot of 1/2" X 96" construction grade plywood and staggering the joints lengthwise. They are very stable and strong.
http://www.howelumber.com/microlam.htm

Gerald D Mon 01 December 2008 06:29

I would not suggest going out to buy new wood beams for a temporary wooden table. If buying, you might as well get re-cycled steel channels. Here is a ShopBot on wood.

J.R. Hatcher Mon 01 December 2008 10:34

Or you might go to your local lumber yard and see if they have an accumulation of shorts (10' and less), they need to get rid of...... cheap. These things come 40' long and they cut them to the customers needs.;)

DocTanner Mon 01 December 2008 14:55

You could do away with the fancy break out board.

DonRoss

Much better to build like the prints show ;)

domino11 Mon 01 December 2008 14:56

Quote:
Originally Posted by Gerald D View Post
Here is a ShopBot on wood.
Wow, that looks interesting. Mike Richards has some nice cabinet doors in that post as well.

William McGuire Mon 01 December 2008 22:16

Gerald...
What about using a flex hose like on your original, rather than the chain?

William McGuire Mon 01 December 2008 22:18

Another thought...
Didn't you, at one time, mention getting by using 1" X 2 1/2" angle iron without the V grinding?

Talons Mon 01 December 2008 22:52

Hi Ya'll I'm new to these forums and to the cnc. I've noticed one main factor in all threads I've read to date! skimping out! I'm like any married man my shop 24' x 32' is my shop but my wifes storage bay! So i spend a lot of time keeping my space usable and unrestricted! the prupose of a steel base is steady strong support and welded is to reduce the walking of the precision square it forms. There are several ways to make the base portable and not lose stability or intrude on it's intrigity!welded x-braces and bolted in place for one! I'm just startingn to build the MM and i've looked at 100's of homebuilt uints and the MM is the premium unit on the market today!

Talons Mon 01 December 2008 23:01

BTW thanks for great discussion! I too have very tight budget and space! and the open ideas sure help in more then just one aspect. i hope to move mine around the shop with the aid of my car rotating stand i built 20 years ago.

Gerald D Mon 01 December 2008 23:42

Bill, we would still use the looped hose for the x-axis cable control. Cost isn't the only factor in that decision - it is less obtrusive and less likely to get bumped or stood on.

Leaving out the grinding of the angle iron is not a real money saver.

Welcome Talons. I am trying to make one easily readable thread here for the guys who want to work their way up to a "full spec". For some people reading this forum, they get the message "you have to have proximity switches, you must have cable chains on all the axes, you must sandblast and paint, you must use stainless steel fastners", etc. etc. and I think that is an intimidating message. All of that stuff is not essential (stainless steel is actually even undesireable).

The main message I want to give is "Build a machine that pays for itself"
That could mean that the machine must start earning before it is completely finished, which is a good thing.

Back to money saving ideas:

- Scrounge old PC, keyboard, mouse, monitor, table, chair.

- Check your timber supplier for "end" boards, the top/bottom boards of the stacks they purchase. Those boards are slightly damaged by the forklifts and strapping, but they make good spoilboards for the table top. They could be less than half the price.

- don't be tempted to buy old stepper motors unless you are very sure of their specs and how badly they have been treated.

javeria Tue 02 December 2008 02:23

For the PC I would suggest that folks us the Intel Atom Processor and motherboard combo, which comes for under 100USD, you need to just add powersupply (even a 100W will work) RAM, HDD, Monitor, keyboard and mouse.

For the capacitors I use the ones which are taken out of older UPS - they are usually rated at 10000uF 100V which are sufficient for our purpose.

Even the 220V cooling fans come from these old UPS (they still have a lot of life left and I have more than one)

All the steel(80% by cost) I have used is recycled.

for the router i am presently planning to experiment with blender motors - this is towards making a low cost low noise spindle for wood cutting.

I hope I was on topic on the above rant :)

RGDS
Irfan

Gerald D Tue 02 December 2008 02:56

Perfectly on topic :)

Richards Tue 02 December 2008 11:23

I'm a little concerned about the electronics. No one "needs" an expensive enclosure or expensive push-button switches or terminal blocks. But I hope that everyone understands that a CNC router is an electrically noisy piece of equipment. The logic signals that send the step and direction pulses to the stepper driver may be less than 3VDC while the AC voltage to the spindle can be about 340 Volts peak to peak (SQRT(2) X 240VAC). What that means is that the large signals tend to telegraph their signals onto the low voltage signals. That can cause lots of difficult to diagnose problems.

Be sure to separate the signal lines from the power lines. Be sure to use grounding wires that connects all parts and pieces of the machine to one common ground.

My Shopbot shipped without shielded cables. I replaced some of them and left others unshielded.

Although many of us are on tight budgets, remember that trouble-shooting "glitches" can take hours or even days, so use good common sense when you wire your machine. Follow the guidelines that Gerald has suggested. Remember that doing things on the "cheap" requires that you pay even more attention to wiring details.

Those of us who have built a lot of process control computers wouldn't hesitate to build a bare-bones controller, because we have the experience and the monitoring tools to check things out. For the inexperienced, first-time builder, just take your time and know WHY you're doing each step in the wiring process. If you know WHY a step is important, you'll be more prepared to fix any problems that may result.

(Believe me when I say that I've built a lot of bare-bones controllers for a lot of different customers since 1977. Every controller eventually worked. Most worked with a minimum of "fix-ups", but a few took substantial time before I got everything working properly.)

Gerald D Tue 02 December 2008 11:47

I remember the first ShopBots had an E-stop button as an optional extra (at a fee). . . .

This is one button that shouldn't be left out if you are going cheap. But it does not have to be in the signal circuit where its wires can pick up interference. It can just be a mains breaker/switch (or 2 or 3 in series) that goes between the wall outlet and the rudimentary MM control system, with the router also on that circuit. Mount these switches on the stationary table.

Gerald D Tue 02 December 2008 12:11

The screening of spindle and stepper motor cables is not only for the purpose of preventing glitches when your CNC machine moves. The chopper frequency in a VFD, or a stepper motor at high speed, involves high enough frequencies to cause interference on other electronic equipment nearby. See: http://en.wikipedia.org/wiki/Low_frequency . . . . you don't want an aircraft to home in on your MM do you? :)

isladelobos Tue 02 December 2008 13:22

FDA-ISO-CE-UNE-OHSAS-EN
minimum standards required in engineering.
can overcome our beast arround the world?
I think yes.

Gerald D Tue 02 December 2008 22:45

Ros, I am sorry, but I don't understand your post :confused:

isladelobos Wed 03 December 2008 01:59

I think the mechmate, and his security systems, it is possible approved anywhere in the world in any professional installation for industrial engineering projects. (legal workshops and small enterprises).
Based on the standars ISO-UNE-EN-ETC.. these standards, studies in each country, the best way to build and create industry.

Gerald D Wed 03 December 2008 02:24

If you want to avoid problems with the laws in your country. . . . . then you must obey the laws of your country. It is as simple as that.

You cannot tell the judge in your court that you had permission from www.mechmate.com to break the laws! :D

hennie Wed 03 December 2008 08:48

Is steel not cheaper now with the economic downturn?

Gerald D Wed 03 December 2008 09:12

Here are two price lists:
SectionsPlate 20081001 CAPE.xls <----- October '08
SectionsPlate 20081201 CAPE.xls <----- December '08

Prices have dropped about 20% over those 2 months

Fronzel Wed 03 December 2008 11:04

What about using Linux and Linux CNC software like EMC?

Gerald D Wed 03 December 2008 11:17

Good one Fronzel - it is used with success.

WTI Wed 03 December 2008 12:14

http://www.craigslist.org/about/sites or http://www.freecycle.org/

If you have Craigslist in your town (or near your town) your computer will be free. Everyday in the "free" section of CL there are computers and monitors free for the taking.

Mach3 requires a 1ghz or faster computer. I've seen desktop computers offered for free all the way up to 2.4ghz. It seems that everyone only wants laptops nowadays.

Also watch for tube type (non LCD) monitors. 15-21" tube monitors are always given away, often several from the same person. Remember that WindowsXP will run 4 monitors at the same time, this can give you a really big desktop.


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