I didnt get a great deal done today as work is busy but i did manage to fit bracing and also tidy up the ends of the channels.

Im not sure if i should drill for the rails and them disassemble and paint the main frame or just keep going and then disassemble at the end?
Seems to me that it could take quite sometime to shim rails and then have to do it again after painting?
Thanks Andy

BEAUTIFUL corner Andy! Great work.

I felt the same way so I left the rails in place and painted after I shimmed them. I didn't want to go through the shimming and straightening process again.

Ah, true British ingenuity & workmanship, in the mold of Rolls Royce . . . :)

Our sequence is to bulk paint before assembly / drilling / tapping / shimming and then to touch up scars at the end.

Hi, Here are a few more photos of the table with paint on.
I managed to grind the rails this week and im glad they are now done. The skate works great. I was a little worried how they would come out but they are perfect. Its better to angle the disk so it cuts down as if it cuts up the burr on the top edge can stop the skate moving freely. Also keep wiping down the sides of the rail stops the bearings getting tight.

One of the rails had a small kink in it about 50mm long which i did not notice untill i was grinding it then i could feel it with the skate. I filled the hollow side with chemical metal and sanded straight and ground the lump off the opposite side which worked well and saved me buying another lenght of angle.

Shiming bolted tables
Its amasing what you can do with a few shims!
One of my X beams had a bend in it about 3' from the end approx 2mm out.
When bolting the table back together after painting i placed shims in the bolted joints and ive managed to pull the beam straight. It does take alot of time to get it right but it is well worth it. You can adjust how much you want to bend it by adding or removing shims, easy to remove shims with a magnet if you find it bends too much when you retighten the joint.
Note this can alter the y dimention slightly.

Next week i plan to get the gantry and y car finished then start to look at the electrics:eek:
Ive been reading alot of posts on the proxies but it still is not very clear to me, so if anyone has any advise on how to go about wiring them please let me know.
Thanks Andy

Great work Andy!

Yeah, we need to summarise that proxy thread - it is too daunting now.

You are a true craftsman Andy.

I don't know if Gerald and Sean_D are using proxies on their new machines but for a long time they didn't have them. Since Gerald has been right about everything else, I took his word for it when he said I didn't necessarily need them. I've been running my machine for months and haven't felt like I needed them at all. However, I would like something that helps set the Z axis. Just haven't gotten around to adding it yet.

We are not using any switches at present, and not feeling a real inclination to actually fit some. (But the mounting brackets are in place . . . )

I have the same feeling....never needed it. You know where you will start, you know how big your material is, so I have never run off the rails or into clamps. Just takes some practice and a clear mind when setting up.
Further I agree with Dough, that a Z-Zero is helpfull since you do change from one bit to the next and have to Zero the z-axis in between a job.

Well we need inputs from the guys who have it as well - :)

I feel its worth the small investment - I particularly find use when there is a power outage and I need to rehome and restart -

really I don't know how I would do without them -

The Auto tool zero is such a great tool - - cannot do without it now!

My MechMate doubles as a work table in my shop when it's not in use. This makes the proxies valuable for re-zeroing the machine before use, because every use is essentially a re-commissioning of the machine.

If the machine were in constant use, I'd probably almost never use the proxies, although I'd definitely use the Z Zero plate. So I think I'd prioritize getting a work zeroing plate or fixture higher that getting the limit switch proxies going.

What would be your view on simply holding the gantry against the stops when switching on?

Having a z-zero touch plate, do you see a zero-ing purpose for a proxy on the z-axis?

My view is that using the hard stops is just as valid an approach, although slightly less sexy. With the proxies, the process is:

1) one double click, two keystrokes, one push button to turn on machine.
2) safety check for possible collisions with anything on the bed
3) four keystrokes to start the X and Y axis homing. Max execution time is about 20 seconds.

Is it worth the extra $$ and complexity just for this feature? For many, I suspect the answer is no from a logical viewpoint, but yes from a satisfaction standpoint. It's definitely more in the cupholder category than the rearview mirror category.

I do note that at least in my EMC2 based world, running past a proxy limit allows recovery purely in software, because the computer still knows where the machine is. Once you hit a hard stop, you're recalibrating.

I don't have a proxy on my Z-axis, and I see no purpose for one.

I think the common setup operation is to get a specific location in 3D space zeroed so that the physical machine and the program agree. Using the touch-off capabilities of a Z-zero circuit against one or more of three dimensions is a very nice way to do this, and it doesn't involve the proxies.

Brad, I was playing a bit of devil's advocate by bouncing those questions off you :)

One might have to move the gantry, y-car and z-slide a long way to get a home position before switch-on, so the switches would be a lot more convenient, no doubt about that. However, in our situation, the loss of a home reference is extremely rare, so the gantry moving is around about 3 times a year. I think the guys with switches do a homing at every day's switch on.

As far as Andy's question goes here in his thread, I would suggest that one mustn't see proxies as a very complicated hurdle. It is something that can be figured out a bit later.

I have bought the proxy`s but never installed them,when I am finished for the day I go to my 0 points and switch the machine off next morning at start up I just make sure that my z -axis hight is what it was the day before.

Thanks all for the info,
I think i will get her cutting and then see how i get on.
Thanks Andy

She Moves
 

Well i have finally got her to move :).
Its a nice feeling after all that hard work to see it working.

I have the pk296aesg7.2 motors with the power supply supplying 75vdc to the geckos. I have wired them Bipolar series and they seem to be getting very hot. Do i need less voltage to wire them diffirently?.


I think now the learning starts!

Gerald, Thank you so much for making this machine a joy to build. It looks very daunting in the begining but once you study the plans and break it down it is very straight forward. Two months ago i had never welded, tapped a hole or knew what n/c or n/o meant!.

Thanks Andy

Well done Andy - it is the Industrial Revolution all over again! :)

What resistors did you fit to your Gecko's and did you double check the resistance values with a meter? They should be 20 kiloOhm for that motor as bipolar series.

Thanks Gerald, Eye sight is not what it used to be!

Andy,

Good work and the machine looks great.

That's a beautiful looking piece of machinery. Very well done!

Andy,
Very Nicely done!

Thanks all of you, i am really pleased with it.
I am having some problems trying to set the steps per mm in mach3?
The steppers say 0.25 step so 360/0.25 = 1440 x 7.2 = 10368 steps per rev of pinion?
Pinion dia = 30 x 3.14159265 = 94.2477795
10368/94.2477795 = 110.0078967
I have entered this but it is not to scale? Have i missed something?
Thanks Andy

The pinion diameter is measured at half of the tooth height - it is not the outside diameter of the pinion. The accurate way is know the module number and the tooth count. See: Understanding & Selecting gear pinions - setting the steps per mm[inch]

That thread is thoroughly confusing at first, but there is a calculator at about post #27.

http://www.worldofcnc.com/images/Com...e%20Pinion.pdf
Thanks Gerald for the quick reply, The pinions im using are the snb1030 in the above link, sorry didnt know how to put page in.
Measurement Do = 30 which is what i calculated?
Thanks Andy

Ah got it now,
0.25 is the output shaft,
so 1440 steps per rev x 10 for gekcos =
14400/ 94.2477795 =
152.78874554
Thanks Andy

If you are feeding that motor/gearbox full steps, the output shaft would turn 0.25 degree for one full step. (The gearbox ratio factor is included in the 0.25 degree marking). (the error here is that the 7.6 factor should not be considered)

However, your Gecko does 10 microsteps for the motors one full step, so Mach has to feed 10x more steps to get the right movement. (a factor of 10 should be included)

Therefore:
The steppers say 0.25 step so 360/0.25 = 1440 x 7.2 x 10 = 10368 14400 steps per rev of pinion
Pinion dia = 30 x 3.14159265 = 94.2477795
1036814400/94.2477795 = 110.0078967 152.789

It me much longer to get it! :)

Setting step/unit
 

Hi Andy,

On the settings page of Mach (Alt-6) is a button above the reset button called 'Set steps/unit'. Click this button and you don't have to worry about any of the maths, Mach does it all for you.:o

Greg

Thanks Greg, That is really usefull.
Andy

My First cuts
 

Pics of my first cuts:)

Well i have finally managed to make my first cuts.
I was very nervous but all went well and i am pleased with the results :)

I think i need to play with the speed settings as it was great along the straights but when it got to corners it seemed to me that it was moving too fast?
This is the first time i have operated a cnc so its hard to know what is the norm.

Thanks Andy

Sorry the pics arnt great.