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Sherman McCoy Wed 11 February 2009 15:51

Mechmate "Junior", table and gantry welded - Portland,OR
I've been looking to build a machine and learn CNC as a new career, and stumbled onto this site a few weeks back. I've spent every evening since reading all the posts, some several times. The more I read, the more intimidated I got about my lack of tools or electronics experience. Finding pre-made laser cut parts from a Forum member pushed me into making an initial commitment

I just got my box of laser cut parts from Joe "Alabama" today, and they are beautiful. I've started welding some non-critical parts in a friends shop. I'm envious of builders who have their own garages, my machine will be going in to my living room. I've decided to make a smaller, lighter version out of necessity with the idea of increasing the length later if everything goes to plan. Right now I'm going to use 49.3" for the Y axis and 36" for the X axis. I'll have to bolt it together so it can fit through the door of my apartment.

kanankeban Wed 11 February 2009 16:03

Hello Krasch,
Welcome...YouŽll see that this will be fun...and not be really need few tools, and the help off all the members of the forum is awsome.
Congratulations on your start!

sailfl Wed 11 February 2009 17:05


If you been reading all the threads then you know that you can do it. Just keep reading and asking questions.

When you are done, you might want to consider a dust collection system if it is going to be in your living room. I also hope you planning to build one that bolts together so that when you get it done and can make some money you can move it to a better location.

Good luck with your build.

Rad Racer Wed 11 February 2009 20:12

Welcome Krasch,

Reading the threads is a great way to start...lot's of valuable information available. As you probably noticed, there are a lot of great builders on this site that are always willing to help you if your struggling.

Remember to post pictures.

good luck

Sherman McCoy Thu 19 February 2009 06:46

Welding the "car"
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I did my first important welding on the Y-car last night. I found that the parts were so well made (by Joe McLain) that inserting them in the right direction improved my chances of success immeasurably. I clamped everything that might move and bolted in the spider prior to welding. Once I was sure everything was properly seated and square to the world, we welded away. Everything went smoothly except one final weld on the sheetmetal which melted a bit from an errant attack by the MIG - getting the weld settings right was a challenge. I then ground down the welds enough so that they weren't ugly bumps on the sheetmetal anymore. The end result was not as pretty as some I've seen, but the car is dead level and straight as an arrow. A little Bondo and a few coats of paint and it should look factory made.

Gerald D Thu 19 February 2009 06:55

Oh well, you did pick the most difficult welding job to do first! :)

jhiggins7 Thu 19 February 2009 07:34


I also melted some of the Y-Car metal when I welded my Y-Car. I used JB Weld to rebuild the melted metal. Then I used Bondo, as you have proposed.

In my case, the melted Y-Car was at the edge, so Bondo would have chipped out. I also used a orbital sander to finish the surface after applying Bondo. Then I primed the car, noticed some un-evenness, more Bondo, more sanding.:D


Sherman McCoy Thu 19 February 2009 07:36

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Gerald, do you ever stop working? It's got to be "Miller time" in Cape Town by now! It's 6AM here in Portland, and I was up early because I couldn't wait to "get on the boards" with some progress. I've been working on my small form table design(3'x4' cutting area), and need Forum input on the smartest place for bolt flanges for portability, and how to design enough rigidity. I'm using heavy gauge 2x2's and 2x4's for the frame with triangle plate for supports. I'd like the table to weigh less than ~250lbs and fit through a 32" door, so I've shortened leg height to 24" and omitted several cross beams. I've attached a rough sketch of what I think it should look like, but so far have only welded the legs to the x-beams. Any input before I start cutting and welding this weekend would be greatly appreciated.

Gerald D Thu 19 February 2009 08:15

You omitted cross beams, but added back more weight in diagonals. . . . . which are not going to serve any "bracing" purpose. The actual table top does the bracing. Suggest you put the cross-members back in. :)

Also note that the cross members are about 4" offset from the center of the main beams.

Sherman McCoy Sat 21 February 2009 20:38

X-Beams and Gantry
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You meet an interesting crowd at the steel yard. A cross section of Hell's Angels, ex-cons and "immigrants".I was up at 7am on Saturday to purchase 2x2's for the table cross members. and 2x4 tubing and angle iron for the Gantry.1/8th" wall tubing was all I could justify, even though some suggest going thicker. As a result I bought clamp strip too. The angle Iron selection at 2 separate places left a lot to be desired, but I found 3/16" 2.5"x2", and grabbed it.
Off to my friends shop to start welding, or actually, to start drilling and tapping a bunch of holes so I could eventually begin welding. Gerald was right, tapping holes is kind of fun, good thing because I have more holes to do tommorow on the X-beams.
We found that bolting the end caps and clamping the gantry end sub weldment with long woodworking clamps worked best. Never did figure out what a "G" clamp is. In America, they're called "C" clamps, and they wouldn't have worked that well.
The welding instructions were as easy as A-B-C-D, and using rectangle tubing we didn't experience propeller twist(much), nor did we have to use 400lb weights or 10 ton hydraulic jacks to square things up. At least not yet...
We started the X-beams a week ago before I knew it was a boo-boo to grind your welds. From now on, no grinding w/o prior approval. Tommorow, I'm skipping church to weld up the cross member support table so I can bolt it to the beams. It's already looking more like a machine than a bunch of metal, but I may prime and paint something so I can admire the end product.
I also just got my tool steel in the mail and scurried off to a knife grinding shop to have an edge put on it. Nice to know I'll have a Z-slide that's a thing of beauty in just a few days. exceeded my expectations in price and quality.

sailfl Sun 22 February 2009 01:28


It is looking good.

Sherman McCoy Sun 22 February 2009 18:05

Showing my best side- Welding the table
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We made an honest attempt to cut the rails with the rotary grinder and were not happy with the results. The thin blade tended to "float". Checking tomorrow to see what laser cutting goes for. Any price will be a good price, because we couldn't even cut a straight edge on 3/16ths angle iron.
Undaunted, we moved on to the next item, welding the table w/cross supports, where we had considerably better luck. A 90deg clamp helped immensely in squaring everything up. Now we just have to figure the best way to bolt the table to the X-beams.

Sherman McCoy Mon 23 February 2009 18:56

Plasma cutting - not the way to go
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OK, so I call a metal fab shop referred to me by the steel dealer, he quotes me $75 to cut my rails, and I'm thinking, "Bob's my uncle", problem solved. I strap the rails to the top of the Subaru, and trek 40 miles to the middle of nowhere to drop off my angle iron. They've got a nice reception area with all these nice laser cut parts, how hard could it be to cut some rails?
Apparently pretty hard. I told them I was going to be using the edge they cut to run bearings on. They said "no problem." I didn't see a bandsaw or a diamond tipped anything anywhere in their 10,000 sqft shop, which should have been my first clue. On my return 2 hours later I look at my warped, butchered rails and I was speechless. I knew I was in deep kimchee when the owner starts off the conversation with, "this is the problem." I really think I could have done better with a handsaw. I still have hope(although very little change left after this mistake).I'll know if they're salvageable when I take them to the knife grinder to see if he can fix them.
I'm starting to understand why so few MM's have actually been completed. I think I'll drop down and do something like bolt together the skate. Now THAT (I think) I can accomplish.

Alan_c Mon 23 February 2009 22:38

I think in excess of 25 complete running and cutting Mechmates is not "so few" however, try the skate is has worked for many of us and can produce amazingly accurate results - if one has the patience to spend a few hours it takes to do the job properly. I achieved a maximum variation of 0.2mm (0.008") over the length of my rails which were up to 3m long (118"). No flexing disks or divots throughout the whole process.

Gerald D Mon 23 February 2009 23:02

Originally Posted by Sherman McCoy View Post
We made an honest attempt to cut the rails with the rotary grinder and were not happy with the results. The thin blade tended to "float".
Maybe I havn't made it clear enough that one needs to make very light cuts at the beginning, to establish a groove, before piling on the pressure. Under these conditions, I cannot understand why you got "float". Can you maybe think of the reasons it floated?

J.R. Hatcher Tue 24 February 2009 06:33

Gerald and Alan, I agree 100% and would like to add ........

A few suggestions:
1. The finish surface will only be as good as the surface the grinder was sliding on (keep it clean during the process) and how well it was clamped down (C or G clamp every 12").
2. Keep the grinder moving, if the metal gets too hot it glazes the wheel and it will stop removing metal.
3. When the wheel starts to cut through you need to start climb cutting only (saves the wheel)
4. When finished, if you are not satisfied with the surface put a new 1/4"+- thick wheel on the grinder (it won't flex) and make several light runs back and forth across the top until you are satisfied. Note: As you continue with steady pressure on the grinding it will take off the high spots until it's not cutting anything.
5. As you are grinding the 45 degree angles keep both sides equal or about the same all the way down. Leave the flat somewhere between 1 and 1.5 mm.
6. Always wear safety glasses and breathing protection ........... NOW GO MAKES SOME SPARKS.

Sherman McCoy Tue 24 February 2009 09:26

This is what dirt bikers call a "racer's bend"
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Alan, you, Gerald, and J.R. are my inspiration. Thanks for all the helpful input. Those tolerances you've achieved are absolutely amazing. I'm going to redouble my efforts and not report back until I have made some forward movement.

Gerald D Tue 24 February 2009 10:32

Krasch, glad we didn't scare you off! :)

That last banana rail looks usable. If clamps will pull it down flat, the screws at 8" centers will do the same.

HomeMadeCnc Tue 24 February 2009 12:58

I have the same issues with my rails. A little fine tuning required!

Sherman McCoy Sat 07 March 2009 19:23

Making great headway
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I've been working every night on my build and have substantially completed all the mechanical parts. With all the angst I had about cutting and grinding the the rails, the hardest part was tuning the skate. Lets just say I know the guy in the nuts and bolts dept. on a first name basis.I found a grinding disk took off too much material so after an initial pass, I used an 80 grit sandisk for the finish work.
Anyway, I'm tiptoeing into the "kitchen project". In addition to 4-Oriental SG7's, 4-203v's, and a PMDX122, I bought a bunch of parts based on what others have used:
1-PS4N42R12 Antek Toroid Transformer
1-Magnecraft SSR225DIN-DC, 25A Solid State Relay
1-ENSTO Rotary Load Break Disconnect Switch #KSR3.40
3-TECO IEC Contactor #CN-16-F6
3-Relpol Electromechanical Relay(replacement for PIR6W-1P-12VDC)
1-WEG 22mm Non-metallic, Double Pushbutton Operator

I (think I)need to buy:
1-International Rectifier 26MB20A D-34 package
1-Cornell Dubilier Capacitors p#598-DCMC100V103
1-92mm Cooling fan
1-handle for the disconnect switch
4 yards of 12ga wire
1-3 wire pigtail plug

It seems like I'm missing something. Can somebody give me a hint on what else I need to purchase for a basic 110v system so my motors will spin? Also, do I need 3 Contactors, or just one?

jhiggins7 Sun 08 March 2009 08:02


A few suggestions:

1. Your stand-offs for the Gecko heat sink will probably need to to be taller. You'll need to mount the fan under the heat sink, and you'll want to put stand-offs under the fan so air can be drawn under the fan. I used all-thread and several nuts for the stand-offs.

2. Since you are building your own power supply, you'll need a perf board or something like it to mount the power supply components on. You'll need stand-offs for it too. Also you'll need some terminal blocks to connect from the board to your Gecko drives. See the pictures in this post. I point to this one, rather than one of the many others on the Forum since this is my build, so I can answer questions about it. The power supply is in the upper left hand side of picture #4. I used a design sent to me by ANTEK.

3. As for capacitors, see Mike Richards posts on calculating the amount of capacitance needed. I used 2 10,000 MF 100 V electrolytic capacitors.

4. You may want to get some of the DIN Rail mounted terminal blocks for the inter-connect between major components. I bought them from FactoryMation like so many others on the Forum. I bought 100 of one type and even painted some of them to color code them rather than buy 100 each of various colors.

5. You mention wire. I bought this HF wire storehouse. It has several feet of various gauge wire. You need very little 12 gauge wire since most of the currents are very low.

6. I used the wire duct to make a neater looking finished product. It is totally optional. Also, I kept the signal cables separated from the power cables. The signal cables are on the right-hand side of my box and the power cables are on the left-hand side.

7. You only need one 120 volt coil Contactor. Refer to the schematic in the download files.

8. You'll need some heat-shrink tubing. Fry's, Harbor Freight, Radio Shack, or your local electronics parts supplier will have this. You can use a hair dryer to shrink it.


Richards Mon 09 March 2009 07:42

The formula for capacitance is uF = (80,000 X Amps) / voltage. So, 80,000 X 12A / 35VDC = about 27,500 uF. 20,000uF to 30,000uF would work fine. Be sure that the working voltage of the capacitor is at least 125% of the power supply's voltage; i.e., 35VDC would use a 50V capacitor (or higher).

Sherman McCoy Mon 09 March 2009 10:47

John & Mike,

Thanks for all the information, this helps a lot. I'll get working on it.

lunaj76 Mon 09 March 2009 22:04

Don't forget the resistors for the gecko's! Jumper pins, terminal blocks, end caps if you don't already have them.

Sherman McCoy Sun 15 March 2009 20:40

Table finished w/rolling gantry
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After drilling, tapping, and filing about a thousand holes, I've finally got my rails fitted. The table is welded and has shoes, and the gantry is rolling!. While I toyed with the idea of bolting it together, you just can't beat the rigidity of a welded frame. I liked having just 2 sizes of tubing in construction - virtually all 2x2's and 2x4's, and the fact that 2 people can lift it without a crane. Going off-plan made it harder to construct than it needed to be, and getting everything square was a real chore, but at least it's done.

I broke a tap making the clamping strip, and learned that using a level isn't enough for mere mortals if you want to hand tap very straight holes. In fact, it's awful for tapping the holes in the spider because the bolt length exacerbates misalignment. Apparently you can either use a drill press with a reduction gear, or if hand tapping, buy a tap guide. I made a low tech solution from a 2x4 which dramatically improved my results.

Gerald D Mon 16 March 2009 09:27

Good idea on the tapping. We do such squaring up in a plain drillpress - turning the spindle by hand.

HomeMadeCnc Mon 16 March 2009 19:36

I use the same idea with the block but I put the tap in my cordless drill. A little cutting oil and its done quickly.

dragonfinder1 Wed 06 May 2009 08:25

How's the build going? Haven't heard anything for a while.

Sherman McCoy Fri 08 May 2009 09:05

building the MM might turn out to be the easy part
I came to the realization that having a router in my apartment wasn't going to fly with the neighbors, so I've been busy building a shop for the machine on some land I own. It's going to take most of the summer to get the permits, electricity, and get the structure built. I've always wanted my own shop and now I have an excuse to build one.

DeadGuy Fri 08 May 2009 18:09

Hmmm, building a building just to put a Mechmate in? I can see the name changing on this thread from Mechmate "Junior" to "Mega Machmate"


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