Definately a scrapyard challenge

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Originally Posted by motoxy

Any similarity to Jonathan's machine is purely down to plagiarism.

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Problem with plagiarism is, as they always tell you at school, you copy other people's mistakes! I've put the ballscrew on the Y-axis of my machine in a sub-optimal position, which you've copied! It needs to be closer to cutter / between the rails. The problem is everything between the cutter and ballscrew can deflect, as the linear bearings don't offer much support in that direction. I posted more about it here:

http://www.mycncuk.com/forums/showth...h-X-and-Y-axis

(But don't start thinking of two ballscrews like I suggest there - it's excessive! Just put the ballnut on the other side.)

Had to sit in a hospital waiting room today so plenty of time to think about this. I will try to get a sketch up later with a smidgin less plagarism.

Bruce

YEAH!! Just sold my old street fighter so i have the dosherooney for the motors etc.

Right. Here is another thought about the gantry.

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Originally Posted by chip

neh lad for future reference £146 or make and offer,thats where mines from

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Same here (wonder why!), but the postage on 190618666009 is cheaper so Bruce did well. I chose solar.jean at the time as I read that his were better quality, but then he changed the model between us getting it so who knows.
If anyone else can be bothered to read it all, before buying a spindle there's lots of discussion on which is best (4 bearings versus 3, and better bearings versus fake) here:

http://www.cnczone.com/forums/diy-cn...tml#post775132

It seems the consensus is the spindles from linearmotionbearings2008 (i.e. same place we get the ballscrews) are the best at the moment.

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Originally Posted by Jonathan

It seems the consensus is the spindles from linearmotionbearings2008 (i.e. same place we get the ballscrews) are the best at the moment.

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I can back this up as well. I have bought spindles for machines I've built for people from several places and Chai's(Linearmotionbearings2008) are much nicer and seem to be consistant every time I get one, they only seem to change when there's an upgrade. He tends to be slightly more expensive but I think they are worth the extra.

The last one was for my own machine and it was upgraded from the previous one's. The water conections where larger bore and the Wire connector was much better with a dedicated earth, the Amps where also higher 8.5A from 7.5A which helps torque at lower speeds this is much welcomed.!

It's been a few months since last bought one but I will be getting one for a machine soon so will see what the next one's like.!!

On another note.!! . . . I made the same offer you did bruce to the same guy and he declined.?? . . . . Don't figure.! . . Guess you caught him in a good mood Bruce. . Lucky bugger.:toot:

Guess you caught him in a good mood Bruce. . Lucky bugger

Guess we talk the same language (chai chai)

I did not realise when I started this that it would occupy my every waking moment. This is the latest design, Strange thing is I seem to have gone full circle but added strength to the gantry. What do you think, could this be a go?

Bruce

Just had a knock at the door. Nice man had a package for me. One spindle and controller.:yahoo:
Just like to say that that spindle is really heavy?? Now have to trawl web for wiring info.

Bruce (with a big smile)

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Originally Posted by motoxy

Now have to trawl web for wiring info.

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Wiring is the easy part, if you struggle it will more likely be the VFD settings you'll want help with.? . . . It's not hard thou and it's all out there. It's been a while since I setup huanyang VFD but if your stuck just ask. . . . Jonathan will probably know them straight off the top of his head.!

You've got the newer VFD. You'll find the 4mm collet that came with the spindle is not brilliant as it only has 6 slots. That causes it to not grip the cutter as firmly or concentrically as collets with more slots. Get a set of the collets on eBay which have more than 6...

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Originally Posted by JAZZCNC

Jonathan will probably know them straight off the top of his head.!

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I do actually, since before I got the second one I used to change them a lot...this is what I use:

PD004 and 5 are 400 (frequency)
PD009 = 15 (intermediate voltage)
PD011 = 120
PD014 = 2.5 (acceleration time)
PD015 = 2.5 (deceleration time)
PD025 = 1
PD072 = 400
PD141 = 220 (motor rated voltage)
PD142 = 8 (max current, amps)
PD143 = 2 (motor poles)
PD144 = 3000 (rpm display scaling - had to look that one up)

You'll probably find some, or even most of them are already set. PD003 is just the frequency it starts with on the display, so before you press run I'd set it to something low (say 50Hz) to check everything is ok then work up to 400Hz. Needn't worry about setting up the water cooling to start with as it'll easily survive the couple of minutes it takes to test without cooling.

For wiring ... 4-core shielded from VFD to motor, connect earth at machine (spindle mount is probably easiest) and frame and the other end to the earth connection in the VFD. 3 power wires from motor go to UVW in no particular order. If they're the 'wrong' way the spindle will start spinning the wrong way, so to avoid pressing reverse every time just swap any two of UVW wires (like you could on a stepper motor phase). Mains input to RST, pick any 2 any way round as it makes absolutely no difference (since it's just got a 3-phase rectifier in there) and remember the earth, otherwise you'll get a mains shock off the machine frame which gets less amusing after the first few times!

Also make sure the wire close to the spindle connector is clipped to the Z-axis so that there's no tension on the cable. The constant bending otherwise can cause various problems as the wire degrades (took me a while to find what was causing that one), or if you're unlucky it could snap/short and destroy the VFD and spindle. Not mentioning any names :wink:

This picture shows what I mean, though actually I took it to show the air cooling:

Attachment 5216

Thanks guys. I will probably get a chance at the weekend to wire it up just to test. I have to order the ally now for the new gantry.

Bruce

Thats it ordered.

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Originally Posted by chip

they wasnt off the top of his head when he blew up my inverter and tripped the house:wave:

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That was some time ago / first one I'd done except my own, :redface::redface: sorry! Connected the output wires to the mains and the spindle to the input, it switched on as normal (as the protection diodes on the IGBTs will have rectified the mains to power it) and let me put all the settings in. When I pressed run it went bang and lots of smoke... got it to work again after replacing the IGBTs, but something else died after about 30 seconds and I couldn't work out what it was.

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Originally Posted by Jonathan

Not mentioning any names :wink:

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What silly bugger would do something like that.!!. . :wave: . . . . . . . Thou I'm pritty sure this beats my expensive cock up.!:clap:

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Originally Posted by Jonathan

That was some time ago / first one I'd done except my own, :redface::redface: sorry! Connected the output wires to the mains and the spindle to the input, it switched on as normal (as the protection diodes on the IGBTs will have rectified the mains to power it) and let me put all the settings in. When I pressed run it went bang and lots of smoke... got it to work again after replacing the IGBTs, but something else died after about 30 seconds and I couldn't work out what it was.

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and i was worried about dropping the balls out of the screw nut...........

If you are using Sketchup and Using SBr20 rails and rm2005 rails and screw from linearmotionbearings2008, then you can download my models into your models from the warehouse.

jcb121 thanks for that. I had already got 16mm rails before finding this warm and pleasent home they call mycncuk. Would still be interested in seeing your model. Iwill try and put mine up sometime.

Bruce

SBR16 is a bit small ... not the end of the world but 20 or 25 would have been nicer. Did you get 16 for X/Y/Z or just some?

:redface:Just the x and y. I still have to get some for the z and the screw.

Bruce

Yeah Bruce I know that feeling better then I want to trust me. Much better then I want to.

Michael

I have spent an enjoyable afternoon staring at the screen. My problem was enough strength to overcome rorational deflection and keeping everything close. I think I may have cracked it using 100 x 50 x 6.35 al channel. Although I have shown a single section it would be no problem to bolt another piece back to back if it was required on building. The rails are close and the leadscrew is also very close. Tidy.Okay comments please.Bruce

I changed the design slightly for the assy and put channel at the top to support the motor mount.

C section also does not have very good rotational stiffness. If you added another bit on the back that would make an I, better but still adding some rectangular on the back (100*50, or over 100) would make a big difference. 1/4" looks a bit thin to be mounting the rails on.

Two pieces of box section wide enough for the rails on a flat aluminium plate with the rails facing outwards is probably the simplest.

Bruce,

Another option you could look at with that build is two section of rectangular box section and bolt a backing plate or wings to them and bolt that to the gantry uprights as well as the box sections themselves. This will give a good bit more rigidity and either the wings or the backing plate could be indexed to help keep it all true and proper. Drop me a message and I can send you a few files in a format that you can use of ideas Jazz and I worked on that will work. Also take a look at my build log as there are some ideas in there you might be able to use. The following might help:

http://www.mycncuk.com/forums/showth...-machine/page6

If you scroll down you will see one model with sections lifted off to show an idea for the Y axis. That might be a good place to start from and change the solid rail to box or rectangular section extruded aluminium or steel and you would have something that would be a good bit more rigid then the channel. Just trying to help and hope not to offend.

Michael

I may be sulking but I am not offended.
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Just kidding. I know that you guys just want me to be succesful and I really am happy to be guided. I am enjoying this part of the work and I know that I have to get this right now or spend more later.

Big Thanks
Bruce

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Originally Posted by motoxy

I may be sulking but I am not offended.

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Well let me have ago.!!. . . It's my special talent offending!!. . . . Ask my parole officer:whistling:. . . . . Only :joker:on both accounts.:smile:

Bruce I'd be very weary with both the Channel and the angle they could both give you more trouble than they are worth.?
Angle and channel are very rarely 90deg or very flat.! If the angle for the bearings hisn't perfectly 90deg and flat it will cause binding in the bearings. If compounded with the channel the rails are sat on not being square or flat then you'll have a bear of a time with sticking.!
Both the Angle and channel will need bracing to fight flex and resonance, esp where the angle meets the channel used for gantry sides.

Can I just ask why you are using channel,angle and 10mm plate in all your designs.? Do you have the material or a cheap source.?

If you have the 10mm plate then why not build using a bolted and braced design which incorparates the gantry sides to increase strength and ridgidty. If braced enough even 9.5mm plate can make a very stiff gantry and Z axis.

If it's any help here is a link to the stiffness calculation spreadsheet I posted some time ago.

http://www.mycncuk.com/forums/showth...ess-calculator

Thanks

Mr Routercnc That is an amazing spread sheet. okay I can now see box rules!! This was a previous design. I had the plate on which i mounted the rails and this was bolted to the box. The angle at the top and bottom get bolted to the plate and box as strengtheners. Is the angle more trouble that its worth? I cannot find where this was slated before so here is your opportunity. Piccy below.

Jazz i have a limited supply of 10mm plate, 50mm x 6mm angle and a length of 75 x 3.2 box. When i started I was going to make one of those plywood cnc m/c's. Wood I have plenty of. Trouble is you guys have shown me the error of my ways and I know that you are all prodding me in the right direction. Also As I said before this is a bench construction as I do not have access to a mill or c/lathe at the moment.

I can only ask you all to be patient. when you get close to 60 the old marbles fall away a bit.


Edit - Talked about in a pm but not actually slated..

Bruce

Just got another computer. Has seperate video card and plenty of memory. Came without a drive so I am just doing a clean install with xp. I will need to study the board and cards and get some drivers.

Ever noticed how confusing it is to be using 2 computers at the same time. Keep using the wrong keyboard and wondering why nothings happening. Oh well.

Bruce

The last drawing looks good to me so long as you bolt both the plate and box section to the gantry sides.
That spreadsheet is rather good. Same formulas I used earlier in this thread.

Thanks Jonathan. I feel that at last I am getting close to re-starting this project. How heavy 4 core do you recommend for the spindle?

Bruce

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Originally Posted by motoxy

How heavy 4 core do you recommend for the spindle?

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1mm^2 is fine, but I used 1.5mm^2 CY since that's what I have for the stepper motors and it's more efficient to buy the same for all. It's important to use shielded here and earth it well.

Edit: Forgot to mention the reason you don't need so thick cable even though the current to the spindle is higher is it's mains voltage.

Thanks for that Jonathan.

Hi Bruce,

In reply to post #73 I would delete the box section and the 2 angle sections. I would then replace them with either an RHS (rectangular hollow section) of similar depth to the plate, or stack one box section on top of the another and bolt the rails&plate to that. Looks like it would be a reasonable fit based on your drawing.

With the RHS option you could potentially delete the plate, but I think on balance I'd still leave it in.

Hope this helps,
Barry

Like this?

Attachment 5239

(not to scale, 3D cad program stopped working otherwise I'd post a proper drawing)

Jonathan do you ever stop thinking? Between you and mocha I have a pretty good idea about how to progress. I will do a quick sketch and get comments.
Thanks for your help
Bruce

Right, here is redesign 5-1.

Obviously I will need to figure out the best side pieces for the gantry. Am I, sorry, are we heading in the right direction?

Bruce

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Originally Posted by motoxy

are we heading in the right direction?

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You've gone for a pretty generic arrangement now, which is fine.
It will be stronger to put the bearing blocks for the Z-axis on the Y-axis and the rails on the spindle plate. This sort of thing (mine):

Attachment 5249

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Originally Posted by motoxy

Between you and mocha I have a pretty good idea about how to progress.

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Time spent discussing his machine was well spent then.

Hi Bruce,

I meant one of these to keep your re-design work to a minimum. But what you've since drawn is also good.

Attachment 5250Attachment 5251

Routercnc - Thanks for that. The latest soluton allows for the screw nut to travel between the rails which keeps the overhang to a minimum. Apparently I still have a bit more work to do on that.:whistling:

Chip - I realise it may be a bit belt and braces but what I have learnt so far is that strength is paramount. The back plate will assit in the end supports and reduce any rotaional force on the boxes....maybe

Thanks for the comments guys

Bruce

Forgot to mention i order the cabling. I dare not order any other materials as there is still time for a few more designs. :wink:

Cleaned up the drawing a bit and corrected the plate thickness on the spindle mount. I have placed the rails on the spindle plate. I am not sure that I understand why as the increase in plate dimension and the rails being further from the center of the gantry would surely put more pressure on the gantry rails. I am obviously missing something here.

Bruce