Stickers on and cutting #77 - South Australia
 

Hello Everyone,
Building has started! After building 2 home brew cnc routers and disappointed with the performance, I thought it was about time to build a man's machine.
The size will be 3000mm x 1830mm x 250mm.
I have received the steel and have started cutting away.
The steel was bought from a company that sold it in lengths only(9-6m), this worked out to be 45% cheaper plus the steel left over for other projects(?). They also were able to cut the lengths to size so I was able to get it home.
Ordered the V rollers and bearings from Rick Hoback from SuperiorBearing, Australian suppliers wanted 400% more than Rick, maybe there is gold in the Aussie ones:rolleyes:.
I have also ordered the laser profile parts from rnixon.
I found some 640oz steppers on ebay, the vendor also has the G540 Gecko which should be able to run the motors in 'half coil' configuration, I think?(if someone could please agree or disagree with my calculations to put my mind at ease.)
He also has a 48V 12.5A Switching Power Supply.
Anyway, thats where I'm up to, hope to post updates with photos(when i work out how, can't be any harder than EMC2)soon.

Welcome Anthony!

Use the "Unipolar" numbers as equivalent to "half coil" - in both cases you only energize a half coil at a time. The 2.2mH will work (Gecko sez 2.5 to 3.0mH for max output). The torque will need to be derated to the 3.5A the G540 can supply;
if 6.3A = 640 Oz/In and 4.5a = 455 Oz/In, then (as an inaccurate linear guesstimate) you'll have around 350 Oz/In at 3.5A. Do a belt drive to multiple that torque, and it should work. Motors will be loafing, so they should be nice and cool.

Glad to see you have started your build !!!

Welcome Anthony!

Thanks Brad, Mmmm....:o I see where I went wrong. I was thinking 'half the coils half the current' which after rereading other posts it is where others have been 'tripped up'. I was avoiding using a belt drive for now and since my last 2 home brews were under powered (secondhand steppers - missed steps) I don't want just good enough, I will do more research. Thanks again Brad.

Anthony, I wouldn't necessarily describe it as going wrong. Most MMs use mechanical ratios (via the gearbox in the OM7.2s, or belt drives) to get their torque. The G540 supplies enough electrical power to produce enough mechanical power as long as the motor isn't grossly outmatched. So, as long as you do the belts, you were in the zone. If you choose not to have a mechanical ratio, then you will probably want more power from the motors, and you will need to go the more expensive individual driver and Bob route. Depending on shipping costs, it appears that the UIRobot drives may be the most cost effective.

Me, I'd just plan on using the belt drives - you may end up wanting them anyway.

Brass Bushes M1 20 220
 

I should have asked if anyone could see any problems with making the bushes out of brass before I made them.
So I'll ask the question, could bush M1 20 220 be made out of brass?

...with the exception you won't be able to weld them to the spider.
The welding is not required, you can easily tap the spider plate and put the bushing in as a spacer/bushing and it will work just as well.

First machine, I did just that and it's still working just fine.

Sean

Progress has been a bit slow lately, due to work.
I have welded the Y-car and the gantry as seen in the following pictures.
Cutting the rails is not as easy as I thought it would be.
KenC gave me a few tips which have been very useful.
Whether it is good luck or good management I didn't cut the rails to length,
this allowed me shift away from the gouge that I had put in the rail :eek:(see photo) which would have required welding and grinding or a new piece of steel.

I recon you can epoxy glue the brass to the steel spider, or solder... Nothing is impossible....

Welcome and good luck with the build. We to are in Adelaide SA and hope that when my new shed is built we can get back on track with our Mechmate.

Chris

I found grinding the rails is alot easier when i used one of those sandpaper/grinding disc. It can be ground in less than 1/4 of the time and less cost, 1.5 discs for 3.6m worth of grinding. The normal grinding discs kept on glazing up even the grinding is done near the edge of the disc.

That is a great note that I don't think get's shared enough. Start with a 36 or 50 grit and finish with a 80 or 120 grit to polish.

For the new readers, make certain that you have a VERY stiff backer to the sanding disk unit. Some of the backing plates on the disks can be to flexible and not give repeated grinding results. I personally put the sanding disk ON TOP of an actual grinding disk as a FIRM back.

Thanks for sharing.
Sean

I set the skate so that it was grinding in the middle of the disc with the rubber backing where it is a lot stiffer, as can be seen in the photo with the grey mark. It is not the opitmum spot for grinding (cutting tip speed, what ever it is called it grinding terms?).
I think using a grinding disc instead of the rubber backing is a very good idea and would be far better.
I timed my self and it took 1/2 an hour to grind 3.6m and 1/2 an hour to cut with 1mm blade. It has gone from a painfull process to a painless process.

Allow me to add to your caution SEAN.

Cheep grinders ( like the one I used back then) have some “flex” due to cheep bearing or bushing to chaft tolerance making the “stiff” disc still “wobble” out of axis.
I remember to remedy this had to take VERY very light passes in order to achieve a respectable flatness ….and goes without saying I had to replace that “cheep” darn oem bearing after only one rail ( see this)!

Buy good tools once rather than a "cheep" making it hard on you !

Robert ;)

be it cheeeep or expensive tools... we still has to be gentle with them ;)

Base table all made, will post pictures later. dxf shows the design, I don't know how to draw in 3d so it is only 2d. The table is off set so that a indexer/lathe can be fitted on the end at a later date.

Anthony

I'm with Sean, the rubber backing pad will give a second class result in comparison to using a grinding disk as a backer.
I have really tried to get this method out there for all to see after reading it on the forum myself.
I asked Redboards to run some comparison tests before he did his rails and he is a convert of the technique.
As Sean says, run up the grits and by the time you get to 120 Grit, it polishes the rails.

Good luck with your build.

Ross

Ross
I don't disagree with you or Sean.
If I was to to it again I would do as you have explained. When I had read Sean's post I had alredy completed the grinding.
The local Hardware Store only had 36 and 60 grit, so did the main cutting with the 36 and finished with 60. The surface still had machine marks so I draw filed with a 12" finishing file.
If some can tell me a good reason(s) why I must have 'polished' rails (apart from me being able to see myself combing my hair) I will do it, I think it is acceptable.

Hi Anthony

The accuracy of the rails are the only consideration, everything else is really only cosmetic. Small scratches will not interfere with the operation of the machine.
The section of rail you have shown looks to be the goods - well done.

Regards
Ross

Not just for combing your hair, Polishing the rail is also a great way to kill time. :)

Anthony,
No reason to polish the rails. I guess to be accurate, I shouldn't have used the word "polish" and should have said - final finish pass. I treated the milling procees like any other metal removing process by using a "rough cut and removal", then a "fine finish pass"

Good luck to all the future builders! It gets easier every time.

Sean

Finishing Build in South Australia
 

Started final assembly yesturday. Found that the cable chain bracket on the main beams were to high and didn't allow enough room for the drive gear(see picture). I lowered it 20mm, re-drilled and re-tapped, no biggy, trap for new players.
Started wiring up today, maybe cutting tomorrow(?!).

...been there....moved that! It all depends on the Diameter of the cable chain you order.

Yes Sean, that was the determing factor of the original position of the bracket.

I would just make the portion shorter that bolts to the side of the machine. The weight of the chain should not be a problem.

Metalhead,
the picture maybe not clear but the bottom of the gear is bellow the thread for the bracket bolts. Yes, cutting the brackets could be an idea if it was only 5mm.

Those bracket legs were lengthened, see the revision note on the drawing 1060215PB. The request came from http://www.mechmate.com/forums/showt...1&postcount=29

Gerald,
I mean no disrespect to the design. I used smaller cable chain than I should have which ment I raised the brackets to keep the top of the chain parallel to the bottom when it is doubled over. Due to the different makes/models and sizes that is used, to help others I thought I would point it out so they didn't make the same mistake.

This is the first forum that I have engaged in and find it difficult to write all of what I'm thinking or what not to write with out offending.

This is the first forum that I have engaged in and find it difficult to write all of what I'm thinking or what not to write with out offending.

Been there….got shot down……rethought my « thinking »…matured for forum exchange….today less aggravated & aggravating :rolleyes:

Think pink, think positive, think to help….if any other….shot the f up and keep it to your self :p
That’s my “moto”
Amiclament, Robert ;)

Anthony, absolutely no offense was taken! I simply recalled that these things were an issue before, and there was a reason that they are fairly long. I added 65mm at the time. The note was also put there so that people can understand why those legs seem so long.

It Writes!!! South Australia
 

It writes! :D:D
A couple wires to tidy up and a couple stickers and I should be making lots and lots of dust/chips.
The second photo is a bit blurd I'll get a better one with stickers.

Looking Good Anthony!

Stickers on and cutting!
 

Stickers on and cutting!
I've been 'going like a cut snake' so that I hopefully get serial No.#77, my lucky number and a good year (1977). So it is out to the Jury..........
The papers on the spill board are the 'Operators Manual' for EMC2, 260 pages :eek::confused:. Always up for a challange.
Anyone got any ideas of what to make/cut/engrave for the Wife as a peace offering? Spent lots of time out in the shed and not enough inside the house with her!

Looking great #77 it is. Is it me or are people getting faster at building Mechmates latlely? Nice looking build !!!

Well done and my your Big Blue give you as much joy as mine.
Is that a die grinder you are using ?

Builder's Log Update
 

Anthony,

Congratulations on completing your MechMate and on Serial #77. Looking good!:)

Here is the Updated Builder's Log.

Please review your entry and let me know any changes you want to make (either by Reply or PM).

Domestic peace offering
 

Anthony,

Chopping board with drain ridges around the edge, aka Aspire demo works as a quick peace offering / demo.

Graeme

Anthony - That was fast !
Are you sure the paint is dry :)

I have not met your wife but just make some money and see what sort of reaction that gets as a starter project.
Of course don't attempt download the gcode for $100 notes and make the money directly on the MM as counterfeiting is most certainly illegal here in Aus.

Well done and enjoy your machine.

Regards
Ross

Long time between posts, so I thought I would show a couple projects completed and update what has been happening.
Every time someone looks at the MM this is the conversation I have...
Visitor: "Wow! its big.. when you said you could drive your car on it, I didn't believe you."
Me: "Yeah, most people don't believe me."
Visitor: "So where did you buy it?"
Me: "No, like I told you the other day I built it."
Visitor: "What! All of it?"
Me: "Yes, all of it."
Visitor: "Even this bit?"(usually pointing to something on the gantry)
Me: "Everything."
It makes me feel proud every time I show someone.

Thank you Gerald for the design and all the MM members that have helped me, as small as it maybe.

Thanks for the suggestions for the wife, I made the 'Mothers Keepsakes' box from the Aspire web site for Mother's Day. The wife loved it. I modified the original design by adding a dado? rabbet? rebate? recess? to the bottom of the box into the sides, which to me means it would be stronger (not that I know anything about woodwork as you can tell). I also had the MM cut the recess for the hinges.
Most of you are probably thing thinking if he doesn't know much about wood why did he build a 'CNC Wood router? well.... my real love is metal so I bought a plasma cutter and the other reason is business. There is a lot more work in the local area for metal cutting, mostly from agriculture.

Kobus, yes it is a die-grinder which just so happens to have the same size mounting hole for the plasma, swapping takes 1 minute.(Saw dust and sparks aren't the best mix and good clean up is needed between swapping).