Machining Aluminum #122 - Sydney, Australia

[pblackburn]

Are you edging ever closer to the end?

[racedirector]

Getting there Pete. I painted the touch up areas with a brush and it turned out a better finish than the parts that were rollered. So my wife bought another can of paint and I plan to repaint the base with a brush each night over this week so it can dry while I am work. Then this weekend will be a mammoth effort to put things back together to at least get me back to where I was a week ago. Purely aesthetics I know but if it doesn't work at least it will look good

[Tokamak]

Best to do it now, once you get it running you won't want to go back and do touch ups.

[KenC]

I second John's take, once it started to move, you'll be too busy making wood dust
*ps, don't worry about the looks, when it works, looks becomes insignificant...

[Bazza]

Hey Bruce
You're CNC is looking great!
Lovely work fulla, making dust very soon going by the rate you build!!
Red is good!
Cheers
Bazza

[racedirector]

I haven't been idle, just quiet. The machine is pretty much back to what it was in the earlier photo minus the base spoilboard. I went on to the control box and had a few dramas with my safety circuit but that got all sorted today so I continued on with all the wiring. A little closer to making things move but far but still far enough away not to get too excited about it

[racedirector]

Bit of a setback, I managed to blow up my PDMX 122 by doing something I shouldn't have. Same incident also took out the power supply on the PC so you can guess what I did.

I have an email into PDMX to get a price for shipping a PDMX-126 to Aus and will send my 122 back to them for repair. If it is fixable I will use it as a spare. Along with the 126 I will also be adding an ethernet smoothstepper to the mix, might as well while I am *still* doing my control panel.

[Tom Ayres]

Sorry to here about the setback, I feel your pain. Lightning took my 126 and the entire PC, I too have thought about a smooth stepper.

[pblackburn]

It will be a nice control panel though...

[racedirector]

PMDX just paid for, will be back in action in about 2 weeks. Will try and get the rest of the machine done by then. Will test a few things with another BOB I have to have it ready for the inclusion of the 126 & smoothstepper

[racedirector]

Back to Mechmate mode after a few distractions.... question of Z motor and the gas strut. I have just connected all the wires together on the motor to check I have the right poles. This "locks" up the shaft making it hard to turn, as it should. I attached the motor spring to the Z motor and then pushed the Z down wanting to see if the motor could hold the Z in a set position just like when I turn the power off on the machine. The gas strut however just dragged the Z back up to full top travel.

This is where the question comes in. Am I correct to assume that what I have done with regards to the motor wiring would be the same if it was connected to the control box but powered off, like when I switch the machine off at the end of the day? Have I buggered up the purchase of the gas strut by buying one that is too strong or can I not determine that until I have all the wiring complete.... as per the previous statement?

I am nowhere near actually needing this in a panic but would just like to confirm the actual purpose of the gas strut in relation to holding the Z up at the end of the day in case I need to buy another lessor charged one....

[darren salyer]

When I power off my machine, the Z does not retract, it stays wherever it is when powered off.
My first strut was a higher rating, and would retract my Z to top of travel when powered off.
Hope this answers your question.

[IMMark]

Like Darren stated, Gas strut should hold the z stable or pull it up when there is no power to the machine. I would say error on the side of "slightly" stronger strut, you can always add weight if needed.
Mark

[bradm]

Same as above; powered off, Z stays in place. Your test seems reasonable. Key question: Is the Z at full weight (spindle or router installed)?

Without my spindle (or dust foot, for that matter), mine would drift upwards too.

[pblackburn]

Bruce, if it is a gradual rise and there is not any gear reduction (direct drive), I would not worry about it. If the Z stepper has a reduction of 4:1 or higher and it is a very slow rise, I would not be concerned. Unless your steppers are under 400 in-oz I would be surprised if there is a problem. If you are still concerned, you can write a quick program and repeat it 1500 to 2000 times. Use a dial indicator to read the bottom position at the start, simulate resistance of material using a spring (either compression underneath or extension above) to engage during that last 30 mm of travel. Run the program, check the distance again and see if it looses steps.

We use 1100 in-oz Nema 34 steppers to hold and adjust position cranks on 45 ton pill presses where I work. There is a lot of back force exerted back to the stepper and they hold just fine.

As for the position of my Z, it stays in place. I did make a M code to retract the to the top position just like at a tool change and added the call to the end of the post processor code in Aspire. That way when the program completes, the Z always retracts. This will serve 2 purposes, 1. I don't have to remember to retract it so the spring does not weaken, 2. it always the shaft to stay almost fully retracted so the oil stays over seal with the shaft retracted to stop corrosion of the shaft that will weaken the seal.

My dust foot is separate from my spindle so the weight is only the the spindle and Z assembly.

[racedirector]

Thanks guys. It looks like I bought the wrong one. After Brad mentioned the spindle, I put that on and it made no difference, the Z shoots back up like nothing was there. My motors are 640oz-in and are wired bipolar parallel, also will be initially running direct drive before making my own 3:1 or 4:1 gearboxes.

I'll grab a set of bathroom scales (we don't actually own any!) and weigh the Z complete to get a better idea of the strut needed or maybe I can get this one recharged instead to a lesser value.

[smreish]

..or add ballast to the z to balance it.
I did that so I could interchange my spindle with my router without affecting the gas strut.

[racedirector]

Hi Sean

I think I would need a small child strapped on there to slow the damn thing down. I tried to do a video with my phone but it was already at the top by the time I pushed record

[smreish]

lol.....that's funny.

[lonestaral]

How about a couple of Koala's, they would look good on the mast,
or are they a protected species ?.

The gas strut that I got was far too strong.
I used a spring instead.
It is slightly stronger than the motor but from a safety point of view I feel that it is better for the Z to retract if there is a loss of power.
Power cuts and current spikes are not uncommon here.
Better than having a rotating cutter drop into the work or the table.

[racedirector]

Al, those pesky koalas smell bad and are protected somewhat and while they would be cheaper to keep than a child (only needing eucalyptus leaves) I would get in trouble with the wildlife people

I'll be sourcing a new strut when I get the Z's weight, a spring is a good idea but the struts are only about $25.00 so not too expensive.

[Tom Ayres]

Bruce I use a 25 lbs strut with spindle and 14" z , it would mostly hold or go up with direct drive but doesn't move with belt reduction.

[KenC]

Weight the assembly & buy a gas spring rated 10~20% more. The whole idea is to preventing the z-axis fall on its own weight. I personally feel it should hold position when power to the motor is cut; Retract to z-zero position that will be too taxing on the stepper motor.

[pblackburn]

That is assuming that you are not bearing into a cut at the time power is lost. In that case, not much really matters anyway. Holding only is preferred, but I can tell you that I have seen steppers back driven by setup people for more than 10 years now and they still function normally. We have now started to use em clutches so they turn the cranks freely without driving the motors. This was done for ergonomic reasons and not because of equipment failure.

[KenC]

I had my fair share of blackout...
Blackout is always a bad thing during any machine operation. In the case of MM, there are no certainty of lose steps or position run off, one has to go through with the repositioning to be certain.

[racedirector]

Question about smoothsteppers and inputs. I would rather sort this now than when I have my 126 & ESS together.

My primary reason for getting a smoothstepper was to increase the number of inputs available when combined with a PMDX126. However, I can find nowhere in Mach that will let me define the extra inputs. I see a checkbox for a 2nd parallel port and another checkbox to define the outputs of PP port 2 as inputs but when I go into the inputs tab there is nothing extra there.

So where do you define these things? And what is the point of asking a question (in Mach) and then not showing extra input offerings?

[pblackburn]

That is a topic in itself!

[racedirector]

Oh dear, have I opened a can of worms?

[pblackburn]

I am tired and trying to do this from the top of my head. I have 13 high speed inputs with the 126 and 108 cards. I mostly use Brain for the desired handling that is needed for the inputs from the 108. I too have looked into the ESS as an upgrade later this year for better control and additional inputs but as for the appropriate way to handle it would better to look to and post a question at MachSupport or Warp9 (if that is your ESS maker) forums. There is not a lot of documentation out there and even Steve S. at PMDX was nice enough to talk to me about it when I was asking how to transition to a smooth stepper when I do it later this year. When I was purchasing the 108 input I did find some good sites but I did not bookmark them so I am sorry for that. As for the worms, they are hidden beneath the dirt and you must find them.

[racedirector]

Thanks Pete, I know what it is like trying to remember stuff when tired, the above post came from me being frustrated and tired.

I'll download the 126 manual and take a look at that, if it can offer me the number of inputs I need then I'll just use the ESS to drive things instead of the PP port. I will jump on the ESS forum too to ask the question above.

RANT START: What really annoys me is when people sell things and then offer bugger all documentation on how to use the product. In my opinion when a product is over $100 in the DIY market adequate docs should be offered on how to use a product, not just install a product[RANT OFF]

I am actually starting to regret the ESS purchase and having to chase instructions. I *was* going to buy another motion control board from Europe (PLCM-E3) but went with the ESS because I could buy it from an Australian seller. Next time I'll just go with the European one.