MechMate CNC Router Forum

MechMate CNC Router Forum (http://www.mechmate.com/forums/index.php)
-   Construction started, but not cutting yet (http://www.mechmate.com/forums/forumdisplay.php?f=77)
-   -   Making sparks - Wexford Ireland (http://www.mechmate.com/forums/showthread.php?t=3066)

jwt Sat 02 October 2010 12:27

Making sparks - Wexford Ireland
 
Hi all


I'm starting a build in Ireland. Have ordered PK296-03AA motors, and a G540 driver .

Have my steel bom and am going to order the cables and electricals.

Planning to photo and document the build.

I have a few questions I'm unsure of.



Which of M5 10 312/314/322 or 324 would you use with a MotionKing PK296-03AA?

Is everything marked as laser cut profile or bent supplied in the laser cut parts or in the dxf e.g 10 40 388 (z-spring anchor)

as an aside is there anyone supplying Ireland or UK with the cut and bent parts, and where do I get the dxf's from, they have been removed from the download page. (was this deliberate?)

What is the stopper lip for? M1 18 022

Do I need the y-rail clamp strip as per 10 20 235 required if using aluminium and pre made v-rails? Would using thicker walled y cross beams help remove the need for the clamp.

Cabling for the motors, do I use multi cored inside one shield or individually screened cables one per motor

Does anyone have wiring diagrams for the Gecko G540 to the motion king motors?

And last but not least will a 50V 500VA toroidal transformer with a 25A bridge rectifier and 10,000 micro farad cap cover the driver and motors and leave a bit of leeway for an indexer (one more motor, break out board and G203 hooked up to second parallel port)

emmmm apologies for the machine gun style of questions but they've been rattling around in my head for a while now.


Regards John

danilom Sat 02 October 2010 13:07

Keep in mind that the DC voltage after rectifier and capacitors is 1/sqrt(2) of the peak amplitude, in your case 70V if transformer is 50V output

jwt Sat 02 October 2010 15:06

Yep you're right, was thinking of the G203s with up to 80v input, might see if a tapped transformer with 50v and 35v taps is available giving 69V and 48V (allowing for diode drop) respectively or just go with a plain 35v transformer and add a secondary supply for the indexer when that gets fitted.

Thanks

John

Richards Sat 02 October 2010 17:17

The Oriental Motor PK296-03AA stepper motors have 1.5 mH inductance when wired half-coil (which would be the ideal method so that you get more than low to moderate speed out of the motors). I've found that my 1.5mH motors (PK296B2A-SG3.6 and PK296-F4.5A) work very well with a 35VDC power supply. To get that, you need to start with a 24VAC or 25VAC transformer. With a 35VDC power supply, I can easily run those motors at 1,500 RPM. Torque is excellent to about 1,000 RPM.

jwt Sun 03 October 2010 06:52

Point taken Mike, but I'm hoping to get closer to 48V as the G540 is rated at 50V, built to take 60V and makes expensive smoke at 70V.

Does the following make sense?


Ireland runs at 220V, transformer is 240V in 35V out so will deliver 32Vac 45Vdc


allowing for 10% line fluctuation, 10% load dump from something else on the same supply an 10% for just in case 45V gets me to 59V (did someone hear a squeak?)

John

Richards Sun 03 October 2010 07:12

John,

Yes, it's truce that the G540 can take 50VDC, but the motors can't - without overheating.

When you use the formula: 32 X SQRT( Inductance) = MAXIMUM voltage, that translates to 32 X SQRT (1.5mH) = 39 VDC. At 39VDC, and drawing 4.5A, those motors will run at their maximum temperature which means that you'll have blisters if you touch them after they've been running for an hour or so.

You can reduce the heat by reducing the current and/or by reducing the voltage. At 35VDC and at 4.5A, they will still hit 65C, which is my self-imposed limit for stepper motors that can be touched. I've run them as low as 27VDC with excellent results. (Maximum temperature for Oriental Motors is usually expressed as 80C temperature rise over ambient with a maximum of 100C, but at 65C they start to have that hot electrical smell. At 80C you can easily smell them.)

The very popular PK296A2A-SG7.2 motors have a quirk. They are electrically equivalent to the PK296-03AA motors, but Oriental Motor rates them at 3A because of the gearbox. Those motors can be driven at higher voltages without overheating because they are run at 3A instead of 4.5A.

bradm Sun 03 October 2010 07:47

Mike-

I know you know this, but the G540 maxes at 3.5A. So in a simplistic model, 39V * 3.5A = 136.5 Watts, vs 35V * 4.5A = 157.5 Watts. Aren't we talking about lower total heat dissipation at 39v? In fact, wouldn't 48V * 3.3A = 158.4 Watts be a closer match for use with the G540? If it runs hot, drop the amperage by a few tenths?

-Brad

jwt Sun 03 October 2010 11:48

Quote:
Originally Posted by Richards View Post
John,

Yes, it's truce that the G540 can take 50VDC, but the motors can't - without overheating.

...............

At 39VDC, and drawing 4.5A, those motors will run at their maximum temperature which means that you'll have blisters if you touch them after they've been running for an hour or so.

.......................


.

Ah.

ho hum buggerit.


Right so, 25Vac it is. Thanks Mike for taking the time to explain your reasoning.

I'll postpone the power supply for the indexer until I actually require it.

I've found the wiring diagram for the drives from and have decided on 18 awg* 4 core shielded cable for the motors and got a good enough deal to be able to use same for emergency switches etc.

* I know 15 or 16 awg would have been better for the motors but it was cheap and rated at 8 amps per core.


Order going in to supplier this evening for electrical components, steel requires a site visit tomorrow for some haggling/negotiations/arm twisting.


So all that's left is the laser cut stuff. I see there is a supplier for Europe, any one used them?


Regards


John

Richards Sun 03 October 2010 16:15

Brad,

You're right, I totally forgot about the 3.5A rating of the G540; however, running that motor at 35VDC and 3A to 3.5A would still be an excellent combination. That's how I run my PK296B2A-SG3.6 motors. They have plenty of power and still get only moderately hot.

As you know, I believe in using components and values that give as long a life as possible while still doing the necessary job. In a highly competetive situation, where component life must be sacrificed, then running the motors hot by under-rating the Amps and over-rating the Voltage would be acceptable; however, buying new motors every year is not an expense that most would deem necessary, especially when that cost could be avoided by turning down the voltage just a tweak and limiting the current to 3.5A instead of 4.5A.

jwt Mon 04 October 2010 14:19

I've melted my creditcard
 
Quick Update

Today I ordered the majority of electrical, steel and odds and sods.

I'm left with a few items outstanding.


I'm trying to get a quote for yitong number three v-rail and matching rollers.

Hepco v-rails and rollers were coming in a silly money, 1100 sterling plus VAT about 1600 euro :eek::eek::eek:

Also trying to find a European source of module 1 15x15mm rails and 20 25 and 30 tooth pinions or a us supplier with reasonable postage.


And last but not least the laser parts.


John

wintersgillg Mon 04 October 2010 17:35

Bits and pieces
 
John

You could try here for rack and pinion:
http://www.automotioncomponents.co.uk/index.php

No experience of them - just found through a link.

I believe cnc basher on this forum supplies laser cut parts.

Regards

jwt Tue 05 October 2010 01:39

Thanks for that, just sent them an email.


John

jwt Wed 06 October 2010 10:51

Majority of electrical has arrived all bar the motors and the g540

Discovered I forgot to order a rectifier :o

Steel price is coming in at 400 euro plus vat which is better than expected.

Allowing for odds and sods of 200 euro more total BOM will be sub 3000 euro which is better than I had figured.

jwt Tue 12 October 2010 07:46

Brief update

Laser stuff ordered, got a great deal on a spindle and VFD actually got it cheaper by putting in an offer which was accepted. :)

Now have to buy a usb to rs-485 adapter for all of 13 euro from ebay.

Getting to a point where I can get 4 linear guides for X and Y cheaper than I can buy pre made rails and rollers. Seems nuts.

Was worried about the loading on them but after a phone call to a local linear guide supplier he pointed out that within reason the loading is limited by the carriage and having 4, one on each corner, divided the load and there is nothing to stop me adding an extra carriage in the middle with some bracing to divide the load by 6.

So given that the guide and carriage I'm looking at are good for 500kg dynamic (1000kg static) 2 metric tonnes should be sufficient. I think.

Debating using the rails you attach from underneath, no holes to trap debris.
But harder to fit.
But cheaper.
But limit me to C-Channel.
But greater rigidity in the rail.
But rails and v-rollers have greater tolerance for dust and debris
But linear rails can be preloaded to offer phenomenal tolerances
hmmmmmmmmmmmm, I'll let you know the outcome of that.



Still waiting on the oriental motors, no sign of a delivery date from them, 2 weeks now since they accepted payment. :confused:

Steel has arrived at my suppliers. he's holding it for me until I'm ready.

Racks and pinions still proving to be either prohibitively expensive nearby, prohibitively expensive to ship from far away or just down right. expensive:mad: One clown in the UK wanted 1500 sterling plus VAT for 30 foot of rack. I didn't even reply just hung up.

Putting together the control box which will initially be used as part of the kitchen table testing but need no further work to install.

I'm using a G540 which has DB9 connectors. so to aid kitchen table testing and future replacement of cables I am going to bring the cables from the DB9's to a terminal block in the control box and and wire from the terminal block. Has two advantages, nice and easy to change from short cables to long cables or replacing cables. and stops any concerns about plugging and unplugging a DB9 connector handling several amps of current.

Plug the DB9 in once and never remove.



oopsies so far include buying predrilled boxes for switchgear designed for standard 22mm switches then buying 16mm switches because they were cheaper than the the 22mm ones. emmm yeah right

So either see if I can return the switches or the boxes or use washers.
Spray painted yellow washers to make it look like part of the master plan. Maybe plastic milled washers using the mechmate with text engraved in the washer to make it all look like fantastic forward planning on my part. :rolleyes:


John

jwt Fri 22 October 2010 03:59

Moved in to my new premises this week so much fabrication of benches etc so not much done on the MechMate.

Steel has arrived and is marked up ready for cutting.

Ordered linear rail for the X and Y, sticking with V_rollers on the Z for the moment.

Racks and pinions ordered.

Found a mail from Kristina at oriental motors in my spam from 2nd of October saying that my credit card had not been debited and my details were being passed on to a local regional office and I would hear in 2 days.

Well I haven't heard anything, I mailed Kristina for an update and heard nothing back.

So, off to ring bank to see if money was taken, if not I'll go with motion king, expect some questions on suitability given 30V transformer and G540 gecko.

If money was taken much jumping and shouting to commence.


I'm in the UK all next week so I'm hoping to start cutting today and be ready for some welding when i come back.

Off topic, while fabricating some benches I was rushing, was hot and welded away in a t-shirt. The old hands will know what happened but for anyone not used to welding, SUNBURN! Lots of it. The arc emits lots of UV and you either wear long sleeves or factor 50.

My own fault; I knew better but was rushing.


As an aside, I was hunting around looking for a better way of cutting steel than my trusty consaw with a cutting blade.

I remembered my chop saw cuts wood and steel. Evolution rage 3. Goes through steel like butter, no sparks, lovely cut and no burr.

I'll take some photos of sample cuts. Actually must add some photos to this, its a bit text heavy at the moment.

Back to these linear rails.

I've gone for non-through hole mounting, which means you bolt from underneath. No dust traps or blanking caps for holes required. And its cheaper. Fine and dandy for the huge hulking C-channel X beams but a bit of an issue for my lovely 100x50 3mm box section Y beams.

So, what to do. I've had a look at the box section, done some sums and reckon by drilling 12mm holes on the bottom of the box section I can insert a bolt up through the mounting hole in the top of the box and into the underneath of the linear rail.

If that weakens the box, my calculations say it's minimal, but if it does I can always insert drilled and tapped clamping bars on the bottom of the box section inside and outside effectively making a sandwich

BOLT HEAD - - - Clamp Bar drilled - - - -Bottom of box section ----- Clamp bar drilled and tapped

Sounds a bit OTT but we'll see.

Anyway to save myself some hassle and seeing as I use the stuff everyday I'm going to roughly level the MechMate and use self levelling epoxy to provide a nice flat, curvature of the earth flat, surface to mount the linear rails on. I'm not overly obsessed about the actual flatness, it's a nice benefit but I am obsessed about ensuring the rails are parallel to each other. In theory it would make no difference if one rail was even 10mm higher than the other as long as they were parallel, it would just look a bit weird. :rolleyes:

A nice simple dam using packing tape applied to the edge of the beam all the way around and standing 5mm proud will suffice. The beam is wide enough to mean the meniscus formed at the boundary of epoxy to packing tape will not affect the area where the rail will be placed. I can slap the rail in the middle of the X beam as the bearing blocks can be bolted any where to the Y beams.

Once the epoxy cures I can drill my rails using a slightly oversized hole and allow myself some wiggle room to align the rails.

I'll use steel fishing leader line and a 50Kg weight to form a straight edge on the X beam and run a dial gauge up and down the rail on a bearing block to ensure a straight linear rail.

Once one side is done I'll mount the second bearing block and attach a jig, a large square made from angle iron And attach a bearing block for the other rail. By running the jig up and down the rail I can ensure the second linear rail is parallel to the first, basically the first linear rail becomes the master referencing for the second rail.

This is the recommended way to ensure that two rails are parallel to each other, the hiwin document I referenced earlier in the thread covers it as well.

Once the X beam is done I can mount the Y gantry and basically do the same process with the Y. This has an added benefit of ensuring that even if one x rail is vertically higher than the other the Y rail will still be level.

Give me epoxy, duct tape and WD40 and I'll get you to the moon :D



John

jwt Fri 22 October 2010 11:18

6 Attachment(s)
Some pics

rayditutto Fri 22 October 2010 14:14

do you have a specific epoxy in mind?

jwt Fri 22 October 2010 16:55

Good question.

The basic properties required are
self levelling
hard, durable but not to the point of shattering
good adhesion to steel, although that can be worked by keying the surface


http://www.epoxysystems.com/214.htm is not bad

11000 psi compressive strength


More importantly for my purposes its Indention rated to MIL-D-3134F § 4.7.4

2000 lbs sq inch at 30 min for zero indentation so a 25mm rail at 3 inch bolting centres is 3 sq inches per bolt so 6000 lbs of pressure from the bolts, de-rate by 75% to allow for flex in the rail, means the bolts can apply at least 1500 lbs or 690kg


So using http://www.futek.com/boltcalc.aspx?mode=metric

An M6 x 1.0 pitch bolt in good steel should be torqued to 6.5 n-m or 5 ft/lbs resulting in a load of 566 kg

So our M6 1.0 pitch bolts shouldn't apply enough pressure to the rail to deform the epoxy once set.

I'd want to ensure my mix was pretty exact and apply low heat to aid the cure but it should be good enough

I'm open to comments opinions or downright contradictions on this as all my experience in self levelling epoxy is for much lower loading such as air bearings.



John

jwt Mon 01 November 2010 11:29

Making sparks
 
1 Attachment(s)
Been making sparks.


My spindle has arrived with the VFD drive, as have my linear rails and guides, RS485 to USB adapter, mains voltage safety interlock for the cabinet and my laser cut steel.

Picked up the last bits of steel and finished up my last steel cuts.

One side frame done, all cross members drilled and laser cut steel prepared.

jwt Tue 02 November 2010 15:25

Table Welded and Flipped
 
3 Attachment(s)
Apologies for the quality of the pics.

jwt Wed 03 November 2010 11:22

Short day today.

Got the Y Car welded up, the Spider drilled and welded, the z plate and tubes drilled.

John

jwt Thu 04 November 2010 14:00

1 Attachment(s)
hmmm

jwt Sat 06 November 2010 09:51

4 Attachment(s)
Gantry welded and square.

Steel degreased ready for painting

Next up epoxy and drilling linear rail mounting holes, all 170 of them.

Gerald D Sat 06 November 2010 11:56

You seem to be making good progress, but my eyes hurt looking at your phone pics. :(

jwt Sun 07 November 2010 05:56

:o

Mental note to self, bring camera with me

jwt Mon 15 November 2010 14:39

Lots done so far

Everything painted

Linear rails mounted and trued up

I had to make 4 small steel boxes to sit between the gantry and the linear rail blocks, approximately 40mm wide 50mm deep and 25mm high.

Because I'm not using the V rails I had nothing to stick the module 1 racks to.

So I drilled holes in the side of the rack roughly 400mm apart and matching holes in the side beams. Then ran a bolt through, put a nut on the bolt and continued the bolt through the beam with a locking nut. So the middle nut acts as a spacer keeping the rail out from the beam by approx 7mm.

I guestimated the vertical height of the rack judging roughly where the top of the pinion would be. I guestimated badly and ended up having to relocate the swivel point of the motor bracket down by 10mm to allow the pinion mesh and be able to use the arc hole to stop the whole lot wobbling.

All that worked fine and dandy and I fitted the motors and my badly off centric bushes to check if all fitted. Alas the grub screws on the pinion are clashing with the heads of the bolts in the side of the rack. My grub screws stick out about 4mm.

So I either cut the grub screws down and cut a slot for a screw driver or weld the nut that is trapped between the rack and beam, remover the bolt and bolt from inside the beam out through the welded nut ensuring that nothing protrudes through the far side of the rack

Existing scenario is

[head of bolt--------->] - [rack] - [trapped nut] - [beam] - [nut]

Proposed scenario

[rack][welded nut] - [beam] - [<------head of short bolt]

I'll sleep on that one. :D

My cable chains are fitted, ran 7 lots of 4 core shielded cable through and remembered to mark both ends of the cables to identify them, who's a clever boy then :rolleyes:

2 for the x motors, 1 y motor, 1 z motor, 1 VFD feed to spindle, 1 y car mounted e stop and start and pause button s and one spare. Might use that for another e stop on the far side of the gantry.

Control box is mounted, and power supply built and tested and inserted.

G 540 mounted to side of box with heat sink compound used to basically have the control box acting as a massive heat-sink.


So the to do list is
  • Wire motors - half coil
  • Solder up DB9 connectors and wire to a proper connector. Connect motor wiring up
  • Wedge motor brackets down so pinions are NOT engaged and do some basic motor control tests.
  • Fix rack bolts or chop grub screws, which ever is better, easier, fancy grabs me.
  • Release motor brackets and do some gentle tests with hand hovering over emergency stop button.
  • Check and torque everything, including the 168 M5 bolts holding the linear rails.

Gerald D Mon 15 November 2010 20:20

Quote:
Originally Posted by jwt View Post
........So I either cut the grub screws down and cut a slot for a screw driver ........
Those screws need to be tightened very hard, a screwdriver slot won't be sufficient

jwt Tue 16 November 2010 17:37

Thanks Gerald, I thought that might be the case but was having a bit of wishful thinking. :)

After a nights sleep and re-looking at it, I cut the rub screws down by cutting the other end off by about 3mm and reshaping the end. Worked a treat and I was able to torque the screws to the point of bending the key. :D

Got my wiring completed and applied power for the first time.

No Movement or anything fancy, just got a green light on the G540, confirmed the e-stops mall worked and had holding torque on the motors.

Made a booboo on wiring these, on the G540 I have A and B coils

on the 34hs9801 I have A, A/. B and B/

Looking at the picture on the front of the G540 plate I assumed that the top most pin, pin 9 was A and pin 8 was A/

Turns out its the other way around. I'm hoping wiring them backwards didn't do any harm other wise I'll have to use the second half of the motor.

Motor control test tomorrow with a bit of luck :D

John

domino11 Tue 16 November 2010 19:19

John,
If your motors did not heat up terribly and there was no smoke, you are most likely fine. :) You need lots of current or lots of heat to cook a winding.

jwt Wed 17 November 2010 03:49

Looks like my g540 has a problem :mad:

One of the G250x modules is faulty, g540 is showing boith red and green led lit.

If i remove the module all is well.


Its the same module I wired the motor to last night incorrectly.

So I guess I broke something. anyone here familiar with these or could I send the module back to Messrs gecko for a repair? Or anyone got a spare I could buy?

On another note, my 34hs9801 motors wired half coil make a weird noise when sat there doing nothing but power applied and locked. A kind of hissing rapid clicking noise?

Anybody hear their motors making noise when stopped but powered up?


John


All times are GMT -6. The time now is 23:31.

Powered by vBulletin® Version 3.8.3
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.