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CNC Plasma - Group Build?


simonr

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Just added the last (I hope) bit to the cad model.

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I made a cable support out of the excess 8mm bright bar used for the axles for mine. I wasn't sure it would be strong enough, but even with the heavy thick cable on the hypertherm - it seems fine. It's springy, but if anything that's an advantage.

I used an extra shaft collar to stop it dropping through the hole.

I guess this comes under the 'options' category - but I've included the mountings as they will only add pence to the overall cost.

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I also drew up some folding legs - which I'll make tomorrow!

Si

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That's about 10 - so I'll get all the drawings together & place the order!

Si

Is it worth us all trying to get others interested to see if we can get near the 50x price threshold? Most people will be on multiple forums so we could spread the word elsewhere too

I bet there are folks on devon 4x4 forum that would be interested, likewise with mig-welding forum

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Suggest a posting on the mycncuk forum under the builds section with a load of images as you may get some interest along with the bigger cnc forum too ... Some are against commercial advertising though although it is after all a group buy to keep the costs down plus just a kit of the laser cut parts so I could not see too much opposition really

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I think it's best to try a small run first. Though it has worked fine for me - it's inevitable that people will think of improvements to make the build easier etc while they are putting it together. I've incorporated all of my improvements thought of while building in this version but I have no doubt there will be others!

What the 'early birds' get in return for their input is the kit of parts at cost. If I go to a second bigger run, I'll add a margin for the time involved in packing boxes, booking couriers etc.

Si

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That's a fair comment Si I am more than happy to cover time and costs to yourself. You have put a lot of effort into this and many people may reap the benefits. I will have a steep learning curve as I haven't used this sort of software before. Looking forward to a new challenge.

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I think it's best to try a small run first. Though it has worked fine for me - it's inevitable that people will think of improvements to make the build easier etc while they are putting it together. I've incorporated all of my improvements thought of while building in this version but I have no doubt there will be others!

What the 'early birds' get in return for their input is the kit of parts at cost. If I go to a second bigger run, I'll add a margin for the time involved in packing boxes, booking couriers etc.

Si

Sounds like a plan Si. I'd love to be an early adopter but I've got too many projects on the go and not enough space, so unusually for me I've restrained myself and didn't put my hand up! :huh:

I'll let others be trailblazers and order a kit-o-bits in a year or two. As well as the inevitable tweaks to the design, I'd be interested hear the how the cheaper plasma cutters perform...

Matt

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The main differences I can see between my 40A Hypertherm and 30A lower cost Plasma are the neatness of the cut and the thickness you can cut with a given power.

I think with the Hypertherm, the arc is more confined which gives a thinner kerf - but as the energy is more concentrated, it can cut deeper.

I do wonder if you put a Hypertherm torch on a low cost welder if you would not get the same result?

Si

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I've sent the drawings & bill of materials to the laser cutters for a revised quote. Hope to place an order in the next few days. If there's any significant difference in cutting cost, I'll post details.

Si

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OK, I have two quotes back for the bits. They are including and excluding bright zinc plating - which I think would be worthwhile?

Based on a quantity of 10 sets,

1 kit, zinc plated = £227.47

1 kit unplated = £215.47

I will have to order all the same - so if you have a strong objection to one or the other - post below!

Price includes VAT but not shipping. I'll ship using www.interparcel.com so you can get your own quote for wherever you live - but I guess around £10 for mainland UK. They will be shipped from RH12 1SB.

Payment at time of order by PayPal (sent as a 'gift' to avoid their fees).

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That's pretty much the conclusion I came to! You could spend that on paint!

For the bits of box section, I coated the three bits which have rollers running on them with wax and the other two with clear lacquer so they all match!

For the waxing, I rubbed them with a candle, then melted the wax with a hot air gun and rubbed it in (probably the odd double entendre in there ;) )

Si

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goodjob.gif

Si, at the risk of sounding really cheeky, could you include the current ebay item numbers on your BOM ?

I assume a few of us will all buy from there and i'll also assume that most of us haven't put something together like this before - so would make life that little bit easier and probably save you some pm's :)

Thanks for all your work, it's much appreciated.

Gordon

Edit : it's http://www.cnc4you.co.uk/Breakout%20board%20KK01%20CNC%20Stepper%20Motor%205%20Axis-with-Relay

not .com

edit 2 : the little igus bushings are pricey little things aren't they !

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This is the set I actually bought:

http://www.ebay.co.uk/itm/3-Axis-DIY-CNC-Kit-For-Nema17-Nema23-Nema34-Motor-TB6600HG-Stepper-Drivers-5A-/351199299894?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item51c51c0936

The stepper drivers are OK, but the breakout board feels very cheaply made. However, it does work! Originally I bought the set because it was cheaper than buying the drivers on their own and put the breakout to one side and bought a USB board. After finding that didn't support THC, this one has been put in to service.

The Igus bushes are expensive if you just consider them as a tiny bit of plastic. However, I've used their bushes on big machinery and even for wishbone bushings running in mud - and they are truly remarkable! They just last & last even in dirty, abrasive environments under high loads! I made a concious decision to use them for that reason but I think they work out cheaper than using similar sealed bearings or bronze bushings.

You could use these:

http://www.skiffy.com/docs/menufr.cfm?pagina=start.cfm&country=uk

And drill the holes out from 9.6 to 11mm. Skiffy are happy to send free samples (add several samples of the same to your cart to get several!). Shorter life expectancy, but probably good enough. They do an equivlent of the IGUS bush - but only for 2mm thick plate not the 3mm I've used. Guess you could counter-bore it a bit!

Not keen on putting the ebay item numbers in the BOM as they will only be current for a max of a week - and maybe as little as a day. I wonder if there is another option like title or what to search for? If I'm going to do it, I'd rather not have to do it twice (or more!)

Si

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That's fair enough - but there are many right answers!

At 24v there is little to call it between the different stepper drivers for this application - other than cost and delivery time.

Likewise for Stepper motors so long as they have similar torque ratings

Breakout boards differ mainly in the documentation provided. Generally the more expensive ones have good documentation and often give you the settings for Mach3 too. If you are more familiar with the setup a cheaper one is a fair option.

USB breakout boards are best avoided if it's your first time - it just adds another layer of complexity to figure out. Thus you need a PC with a Parallel port.

All the mechanical components you can select by their specification.

Si

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