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Drexel Tue 22 April 2014 07:29

Still plugging away - Rose Hill, KS
 
Have been thinking about a CNC machine for a long time. It just seemed to be such an overwhelming project that I kept putting it off.
Unlike many on the MechMate forum I have no experience in anything it takes to build a MechMate except a bit of welding (I’m not a welder but I can get two pieces of steel to stick together).
I had a set of plans that I had downloaded years ago for another CNC machine but after looking at the MechMate and lurking around the forum for awhile I erased those plans from my computer, bought a set of MechMate plans from Mike and 700# of steel from a local supplier. My plan is to build a 4x8 so I can work with standard size plywoods etc.
Other than seeing how pleased all that had built a MechMate were the helpful attitude on the forum and the vast amount of knowledge available is the thing that sold me on a MechMate.
I have had the good fortune of meeting Jim (MechMate #104) who has kindly offered his assistance. If I end up with a MechMate half as nice as Jim’s I’ll be overjoyed. It is a beautiful machine.
Jim on the other hand is not so fortunate. When Jim said that a good straight edge would come in handy and I told him in my world that would be a 2x4…he cringed. I can only hope he realized I was joking. I do hope Jim survives this build; he seems to be such a nice guy. :D
Anyway, here’s to building something far and away more precise and complicated than anything I’ve ever tackled. I’m retired so at least time won’t be an issue.
John

smreish Tue 22 April 2014 08:26

Things to consider for your build
 
John,
Welcome to the wonderful world of MM.
By your humble admissions, you have exactly the keen attitude needed to build a MM.
The skills required are not complex....simple fabrication methods are used to achieve great results.

The advice I would offer to you or any newcomer is to be comfortable with doing everything twice! Read 2x, measure 2x, cut-weld-cut-grind-etc...2x.

The MM is a mechanically simple (plumb, square and straight) are the keys to a great machine.

-The key tools that require a good (okay - great) set up are:
-Drill Press (with run off tables to hold the long steel members)
-Drill press hold down vise (all the small parts)
-A very good drill bit index
-The good machine driven spiral taps for threading things
-scribe and center punch
-grinder (with both sandpaper discs and real grinder disks) - key to a great rail system


Good luck on your build!




[/LIST]

JamesJ Tue 22 April 2014 19:10

Welcome to the forum! Whew!! I was afraid that the 2 x 4 thing was real! :)

I think it is safe to say that the forum has another quality member and will benefit from John's participation.

John, It was great to meet you and I look forward to being part of your journey.

Jim

darren salyer Wed 23 April 2014 05:48

Welcome to the forum!!
Great group of people here.

Drexel Sun 01 June 2014 15:08

Still plugging away - Rose Hill, KS
 
2 Attachment(s)
Introduced myself awhile back, thought I'd let everyone know I'm still alive and going after it.:)
I'm trying something a little different in the mounting of my hardened rails. I'm using alum but the alum I'm using is alum tubing cut in half. Not sure it will have the strength needed but if not theirs always "plan B".
I know many start with the elec first but I tend to gravitate to that which I know at least something about. Besides this way I'm committed:D
Had I started the elec first I might still be pounding my head against a wall.
Fortunately I have someone who's built a MechMate and who knows elec and he's only 1 1/2 hours away who has kindly offered to help.
Ordered the MechMate kit from Rick (bearings rail etc) waiting on that to arrive. I ordered the motors, five PK296A2A-SG7.2's (one for a spare) Ordered a bunch of other elec part, connections etc. I'm going with the Gecko G540.
I Need to get the rack material I have cut and welded, need to prime and paint the gantry etc, etc. I know how to eat an elephant just didn't know how big this elephant was:eek:
I'm including a couple of pics. If anyone see's a screwup let me know. The quicker their caught the easier and cheaper they are to fix.

Rapid Sun 01 June 2014 15:16

Hi John.... keep plugging away.... I'm just getting started. I am surprised to learn that a Gecko 540 will do the job but there are other machines here successfully running them. My little diy 2 x 4 router uses them. Makes for an inexpensive and easy to do control. Are you using Mach or Linux ?

darren salyer Sun 01 June 2014 15:42

Looks like good progress to me.
That's a couple references to eating the elephant lately. I love it.

Drexel Sun 01 June 2014 16:59

I'll be using a Windows based computer and will go with mach3 though I've not purchased any software yet.

Rapid Sun 01 June 2014 17:40

Well I don't want to ruin your day but I'm wondering how grinding aluminum rails is going to go for ya ?

My diy 2 x 4 router uses Anodized aluminum rail with Igus plastic linear bearings.... which is probably ok for a small machine. I am just thinking aluminum is going to wear down fast .... but I am no engineer.

Oh well maybe you can salvage the aluminum for another project or mill it on your soon to be finished and numbered MM.

:)

.......... at least you don't need to worry about them rusting !

Drexel Mon 02 June 2014 01:54

Thanks Rapid
I'm not grinding the alum I'm using them to mount hardened rails to. Normal 1/4 inch alum has the beefed up inside corner just like regular steel angle. This beefed up inside corner kicks out the bottom of the rails. From what I can tell those using alum to mount rails to use architectural alum which I'm assuming is stronger and doesn't need/have that beefed up inside corner. I don't think most places carry architectural alum, at least I'm not finding it locally. Someone mentioned a place in Dallas, Tx that has it. I did some checking and this place also has a branch in Tulsa, Ok. Bottom line is I'm being cheap and figured I'd try this before paying for special alum + shipping.
I may regret my decision but the way I figure it is if it works I may save future builders a little money. If it doesn't work I'll have saved them time and money by not having to try it themselves. :)

Rapid Mon 02 June 2014 05:44

Ok I get what you are doing. Some are using hardened rails but it is not necessary. I am not sure how much benefit you get down the road.... but I have not considered the increased cost either.

So you are attempting to cut the cost of using hardened rails by mounting on a less expensive grade of aluminum.

smreish Mon 02 June 2014 08:30

The reason ARCH aluminum was called for in the alternate design was because it has a square inside corner instead of a fillet w/ radius.
If you look at the plans closely, the aluminum angle is cut down with a very ROUGH tool (like a table saw) and cut short by about 1/32" of an inch to allow for a gap to occur UNDER the shoulder of the BWC preground hardened rail. By doing this, the bottom reference of the precise rail system is maintained and the precision of the cut is eliminated. The BWC rail sits on the inside of the bottom leg of the angle and bolted to the upright leg of the angle.

This allows for a DIY manufacturing of the rail with simple tooling.

If you have any questions....ask away.

pblackburn Tue 03 June 2014 16:15

Quote:
Ok I get what you are doing. Some are using hardened rails but it is not necessary. I am not sure how much benefit you get down the road.... but I have not considered the increased cost either.

So you are attempting to cut the cost of using hardened rails by mounting on a less expensive grade of aluminum.
I will speak from the point of my profession as a machine repair technician in the manufacturing industry. I work on many machines and the number one thing that affects any of them is wear. The hardened V rails addition costs an additional $500. The benefit is the wear reduction on the rails. Wear should always go to the consumable part. That part should not be the X rails but the wheels. If you are doing a lot of small work in the relative same location it will develop more wear at that point. Most machined wheels are typically made from a tooling steel and this will be harder than your rails. Wheels are easier to replace than rails. If you are cutting sheets all day long you will have more even wear so it will not be as noticeable. With properly hardened rail and wheels, the harder surface also translates into a smoother roll of the gantry and Y car. While I made the choice to use the hardened rails and wheels, I did not use aluminum but cut down the angle iron instead. I have more resources available than most do to use. I will say for the person who does not have the machinery available to do this; it would be daunting, adds a bit of complexity and would be more costly. Would I recommend the rails from a wear standpoint, yes. Is it absolutely necessary...No.

Rapid Tue 03 June 2014 16:44

Thanks Pete... I have just read the V cap thread and now I understand. When I said using hardened rails is not necessary I was parroting remarks found elsewhere in this forum. What you say makes perfect sense. On my 12 foot table I would be tending to use the 4 foot of space at each end and the 4 feet in the middle will be traveled over less often.
.... now I have this issue to ponder.... and maybe John will be able to make his $ saving modification work

KenC Wed 04 June 2014 01:23

If you are serious about wear and tear on the wheel & rail, you can also use plastic wheels. It will not out last the rail, at least not in this universe.
Another bonus is that it will wear down evenly. & may cut some cost too.

Rapid Wed 04 June 2014 04:49

The $500 additional cost Pete mentions becomes about $750 if you build a 5 x 12 machine
If you do go with MM rails I am assuming you can regrind them should you experience uneven wear. Decisions decisions decisions.

KenC Wed 04 June 2014 05:48

Make your own plastic wheel & you save $100~200. the difference would be nearly $1000.
I just love cheap solution. don't have money for over spending....

pblackburn Wed 04 June 2014 14:01

I would not price the rails through McMaster. They are way out of the ball park on pricing.

smreish Wed 04 June 2014 14:20

Call Superior Bearing in Canton Ohio....best price on wheels and rail

Drexel Sat 07 June 2014 04:18

I bought my bearings, bushing and rail from Rick at Superior. Superior has sold enough to MechMate builders that Rick has put a kit together. My cost was as follows

GW3 = $15.95ea @ 14pcs = $223.30

B3X = $3.91ea @ 6pcs = $23.46

T3H-10’ (see Note) = $108.60ea @ 2pcs = $217.20

T3H-6’ = $65.16ea @ 2pcs = $130.32

T3H-3’ = $32.58ea @ 2pcs = $65.16

Total Parts = $659.44 (5-14-2014)

Shipping by UPS Ground to Residential in Wichita, KS = $34.88

Total = $694.32
Note: We will cut the 10ft pcs into two pcs each. One will be around 9’ and 1’, and the other will be around 8.5’ and 1.5’.

I had the rail cut down to save on shipping. I placed the seams in the rail to the end of the bed where it will not be used as much. I ground the bottom part of the rail very lightly to make sure the crown of the rail would match up. I drilled and bolted the rails 3/4 of an inch from where the rails pieces meet (the rest of the railing was bolted at three inch intervals). I can hold a bearing in my hand and roll over the seam without even feeling where the two meet.
Lets see on a 10' piece of rail that's 41 holes to be drilled for the railing 41 holes in the alum times two rails...That's a lot of holes! It actually went pretty quick, about 3 1/2 hours per side.

jhiggins7 Thu 12 June 2014 05:49

John

This is not directly answering the question you asked Pete on his thread, but many of us have used shims like these to "level" our rails. Since you are likely only going to do this once, the shims are a pretty good solution. Some have even made shims out of aluminum soda/beer cans.

Good luck with the rest of your build.

pblackburn Thu 12 June 2014 12:32

If it is indeed the rail you are shimming, Precision Brand makes thickness gage available in 5', 12' and 25' lengths. This is assuming the error is constant over the distance of rail. It is 0.500" in width.

Drexel Thu 12 June 2014 15:31

Thanks guys. Pete your right about it being the rails and not the beams. My beams are welded to the legs so they are where they are. I'm needing to raise the outside of the alum for my hardened rails about a 3/32'nd or so. Even if I have to shim each bolt in the end a 12' piece of shim would get me off to a good start. Might keep me from having to use so many small shims.
I welded the beams to the legs by placing both of them on a very flat surface. I never considered that the top and bottom of the "C" channel might not be the same length/depth. I welded the beam to the legs with the flat side up. If I were to do it again I would do my shimming on the beam before welding. Live and learn. I'm glad it's only off as little as it is.
Hope this explanation is better then the last one. :)

Drexel Tue 21 October 2014 08:40

Ok I've looked hi and low. Where are you guys getting the 7/8's cylinder with the 14" stroke for the Z axes? I've found the 1" (actually 8.8") cylinders 25-30# with a 14" stroke. I've found the 7/8's cylinder in the 25 to 30# range with a 10" stroke but no 7/8's with a 14" stroke in the 25-30# range.
I bought one of the larger cylinders and it just about works. The spider scraps off the paint. I just don't like things quite that close to something that's pressurized like the gas spring is. If I had to I suppose I could grind the spider about a 32nd of an inch but obviously my first choice would be to buy the right gas spring.

pblackburn Thu 23 October 2014 21:00

McMaster has one with 13.77" stroke at 25 pounds and diameter 0.87"

Drexel Fri 24 October 2014 03:59

oops sorry pete I got my decimal in the wrong place. Should have been .88. I believe you may be talking about the one I'm trying now.
On another subject. Something you said earlier about using hardened rails: "I will say for the person who does not have the machinery available to do this; it would be daunting, adds a bit of complexity and would be more costly". You hit it right on the head. I could write half a page on the things hardened rails change. As you implied, not a show stopper but definitely requires different tools and multiple workarounds.
I would advise anyone thinking of hardened rails to read your post.

Drexel Fri 28 November 2014 05:48

Ok, on to the electronics. Got my kitchen table project started. It's going better than I thought it would. Then again I wasn't expecting much. lol I downloaded a file for the G540 from the Gecko web site to setup Mach3. That made things a lot easier than trying to figure out pins, ports, high, low etc.. Easier but not foolproof. After about two hours of research and looking at all of the pins and ports settings (Like I'd know if something was out of place) I realized I hadn't set up the 25 pin parallel port to talk to the G540.
It's been said that ignorance is bliss. I beg to differ. The entire time I'm trying to figure out why the motors wouldn't respond I'm thinking..you know your only two minutes from having the motors running if only you knew what you were doing.
Once I put the proper number in it's proper place in Mach3 I pulled up the Road Runner file and hit start. Seeing those motors start, turning this way and that, It's enough to make a grown man giggle like a little girl. It was indeed a sight to see.
I then decided I'd hook up a lamp and try getting the lamp to come on, simulating a router.
You can get just so far on luck when your ignorance catches up with you. I hooked up the lamp to the solid state relay, hooked up a 12vdc supply to trigger the ssr and turned on the power. After I got back from the basement where I had to go to reset the breaker I realized I needed a new ssr. I did get the lamp to come on just couldn't get it to go off. Not sure but I think that's what happens when you short out an ssr. After looking at the diagrams a bit more I think I've figured out what I did wrong. I ordered two ssr's for my next attempt. On the bright side ssr's are under $20.00 and G540's are closer to $300.00 and the G540 appears to be ok. The motors still run. If I get through this with no more then a couple slightly burned cornea's from the electric sparks I'll figure I've done ok. :-) Stay tuned for the next episode...

MetalHead Sat 29 November 2014 04:56

It is fun to experience when you take a knowledge step with this technology.

Learning is a great thing, but smoke aint cheap :) !! Be safe !!!

Duds Sun 30 November 2014 12:03

:) sounds like your having fun with smoke. One of the first things I did at Tech College when I was an apprentice was wire up a power supply backwards with 240v on the secondary and 24v on the primary. It took out the service fuses for the entire building. Sprayed me with oil and snot from the exploded caps and scared me witless with the bang. In all the confusion with the power outage nobody figured out it was me. My teacher knew but he wasn't going to say anything either.

Drexel Mon 01 December 2014 04:42

That's the kind of lesson you don't forget!
On the bright side. The second solid state relay made it out alive. Alas I did have to make a phone call to another MechMater for a little help.
I had the ssr hooked up and was reading 118 vac at the plug that the light/router was plugged into but still no light. I plugged the light into the wall to make sure the bulb was good and the light came on. Ok, this ain't right, 118 volts and no light?
I've been reading a beginners electronic book (better late then never) and suspected a lack of amperage. Now I know I'm over my head (haven't gotten to that chapter in the book yet :-) ). I called Jim #104 and explained my problem. Jim doesn't use the G540 on his MechMate but got online and looked at the schematic for the G540 and explained how to go about figuring out my problem by drawing it all out and testing with a nine volt battery. Two things that helped a lot was finding out the load the G540 instructions was talking about was not the light/router but the solid state relay. The second thing was that the G540 wasn't sending out a voltage signal to turn on the light but was completing the ground. With those two tidbits of knowledge the circuit made more sense.


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