simonr Posted October 8, 2014 Share Posted October 8, 2014 A while back, I started designing what I hoped could turn in to either a plasma kit, or an open source design. I dug it out this evening - and worked on it a little more. It's based on 50mm x 1.5mm wall Box Section which is strong but very light plus bolted together laser cut & folded brackets. The brackets are attached to the box section by running M6 studding through the box section and using it to pull the brackets in towards it. The carriages run on the corners of the box (as they tend to be the straightest and strongest bit) on Nylon V-Groove bearings. It's driven by 5mm pitch x 15mm wide timing belt on 20 tooth pulleys. I've not drawn the Z axis (torch height) - but that ought to be fairly straightforward. You can see 'perforations' in the middle of each of the folded end plates. My idea was that you could saw these in half and extend that axis if you wanted a bigger table. Initially it has a cut area of about 700x1000mm, the 1000mm set by the length of the box section. While this probably seems small, I wanted something I could store easily. It's rare for me to need to cut anything bigger. My idea was that it would fit on a Euro-Pallet, which can also be used as the cutting bed. Si Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 8, 2014 Share Posted October 8, 2014 That's a nice design Simon, I could see that selling as a kit of parts that excluded the box section. The only issue I'd see with selling it as an almost complete kit is you may start getting lots of 'support calls' that aren't related to your kit but are more to do with learning to operate a cnc plasma cutter. If the above design had been available as a kit before I started collecting the parts for my build I'd have bought it. Nice work Quote Link to comment Share on other sites More sharing options...
zim Posted October 9, 2014 Share Posted October 9, 2014 Very nice. Why not use angle iron on the ends to give it some rigidity ? G Quote Link to comment Share on other sites More sharing options...
simonr Posted October 9, 2014 Share Posted October 9, 2014 Zim, it does kind of! Just Laser cut & folded to form an L section. Si Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted October 9, 2014 Share Posted October 9, 2014 Why not use Ali section, rigid enough, easy to drill and cut, you can get the extruded sections with the little nuts that go in the sides for easy assembly and adjustment. Obviously it's more expensive but in the grand scheme of things it's probably not too bad and lighter to post. Use loads of it at work for things like this. Quote Link to comment Share on other sites More sharing options...
simonr Posted October 9, 2014 Share Posted October 9, 2014 Have any of you found a decent source for the straight plasma torches? Or are you using a standard crooked one with a more elaborate mounting? Si Quote Link to comment Share on other sites More sharing options...
robertspark Posted October 9, 2014 Author Share Posted October 9, 2014 standard hand torch (PAC110) - Hypertherm Powermax 350 (old one now, works fine for me). hypertherm "straight" (machine) ones are only available for the bigger machines (600's, 1000 etc), no idea about other manufacturers. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 9, 2014 Share Posted October 9, 2014 If I do go for a machine torch I'll have a look on http://www.riverweldstore.com/index.php and see if I can find one that takes the same consumables as my hand torch. I've bought stuff from these guys before and had no problems. They seem to have a few body only ones available which should make shipping cheaper. http://www.riverweldstore.com/index.php?main_page=advanced_search_result&inc_subcat=1&search_in_description=1&categories_id=&keyword=machine+torch+body Quote Link to comment Share on other sites More sharing options...
robertspark Posted October 9, 2014 Author Share Posted October 9, 2014 question.... can you change a plasma torch to a cheaper one (or a machine one) with cheaper accessories (such as can be done with a MIG and the fairly well known MB15 torch)? I can vouch for riverweld too, used them before, stuff always arrived Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 9, 2014 Share Posted October 9, 2014 I believe you can, the main issue will be to do with the ignition system and any safety interlock stuff. EG if you have a pilot arc machine you still need a pilot arc replacement torch. Hypertherm use something called a blowback ignition system .... I don't knbow how that works but I believe it is only used by hypertherm. This is just guess work though. Quote Link to comment Share on other sites More sharing options...
simonr Posted October 9, 2014 Share Posted October 9, 2014 Probably better to stick with an adaption to fit a hand torch. A straight torch just adds expense I guess. I drew up a Z-Axis assembly, but I don't like it very much! Using largely off the shelf components, the cost soon ramps up. I have another version in mind though! Si Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 9, 2014 Share Posted October 9, 2014 I recognise most of those components from my ebay searches It is very easy to spend a lot of money on the Z axis. The screw I think is a necessary evil, but at least one of the commercial systems just uses a piece of plate running between 4 v bearings instead of linear bearings and rods for the slide. Quote Link to comment Share on other sites More sharing options...
robertspark Posted October 9, 2014 Author Share Posted October 9, 2014 I'll get some closeup pictures this evening of mine and post them, maybe they'll give you ideas. I must admit that the z-axis although workable is not the most robust, but it does work and is cheap to make. For anyone interested, (OT-landover related though), but I'd suggest searching for rack and pinion on ebay.com as the costs coming in from china or turkey appeared more cost effective than on ebay.co.uk. there is also quite a bit of trapezoidal (search for TR10x1.5 or TR10x2) lead screws and delrin nuts / trapezoidal taps & delrin rod. If you want or need improved accuracy on the z-axis. My z just has a bit of M8 threaded rod and a long M8 nut so there is a bit of play, thought about making a delrin one to remove some of the play maybe. When I looked at making carriages I was looking at using standard available steel sections, and tried to avoid bent / double bent sections because of cost + accuracy in forming the bends, and increasing the complexity, hence I looked at getting oversize box and using that to ride over smaller box. If there are a set of plans available I'm happy to have a go at cutting some patterns out for someone (think of it as reprap), if we can build one, that can always be repeated if there is an interest about. Don't want to hijack LR4x4 with cnc stuff hence quite happy for a mod to advise if there is interest / not in this or whether its way OT. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 9, 2014 Share Posted October 9, 2014 I'd say you are firmly on topic Robert, this is afterall the tools and fabrication section of the forum There are at least 5 people interested in this thread so I reckon we're pretty safe .... and of course you can't argue that this isn't a technical topic either Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 9, 2014 Share Posted October 9, 2014 With regards to the cutting parts, I'm fairly certain that once mine is up and running the first parts I'll cut will be replacement parts that look neater Quote Link to comment Share on other sites More sharing options...
simonr Posted October 9, 2014 Share Posted October 9, 2014 And a better one. Ignore the fact that it is a trapezoidal thread - i couldn't be bothered modifying it. It's just a plain nut on M12 Studding held in a hexagonal 'keeper' so it doesn't rotate. This arrangement has taken about £100 out of the Z axis! Apart from a mechanism of attaching the torch, it's fairly complete! Just need to get a quote for cutting & folding all the bits! If any of you have Solidworks 2014 - I'd be happy to share so long as you don't publish the model (I'll do that!) Si Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 9, 2014 Share Posted October 9, 2014 Nice, that's quite a saving. Quote Link to comment Share on other sites More sharing options...
robertspark Posted October 9, 2014 Author Share Posted October 9, 2014 photos here: https://lh6.googleusercontent.com/-30OtDHW3sxs/VDcUORf75ZI/AAAAAAAABjw/YFiRnRiMLdU/w399-h534-no/IMG_1145.JPG https://lh5.googleusercontent.com/-Px8SESFtOSM/VDcUmtPtlXI/AAAAAAAABkU/ufsPDWcFRsY/w399-h534-no/IMG_1148.JPG https://lh6.googleusercontent.com/--Gn1DwNQ_SQ/VDcUojQGYVI/AAAAAAAABkc/XsjEQq0ztOc/w399-h534-no/IMG_1149.JPG https://lh4.googleusercontent.com/-7PnUQB7D7uQ/VDcVG5tnENI/AAAAAAAABkk/MqzTfE9Uwhg/w715-h534-no/IMG_1151.JPG https://lh4.googleusercontent.com/-aqqbRRBgPZo/VDcVI7brHCI/AAAAAAAABks/mhWO6yNFquI/w715-h534-no/IMG_1152.JPG https://lh3.googleusercontent.com/-2rcz8a4HAQI/VDcVNMZ9xgI/AAAAAAAABk0/o_1qPmfduzQ/w715-h534-no/IMG_1153.JPG https://lh6.googleusercontent.com/-vjsY4AQewtA/VDcVf5TVaRI/AAAAAAAABlE/gwD_yONEi3Y/w715-h534-no/IMG_1154.JPG https://lh6.googleusercontent.com/-rwKt9NohPVM/VDcVfO84hnI/AAAAAAAABlA/86iJ2NQ_So0/w715-h534-no/IMG_1155.JPG https://lh3.googleusercontent.com/-2542auN9-oY/VDcVh7bOhqI/AAAAAAAABlM/1rbhdcsQsj4/w715-h534-no/IMG_1156.JPG https://lh4.googleusercontent.com/-y-TsUKpJNE4/VDcVy0lrHkI/AAAAAAAABlU/ypB8oFpvjfo/w399-h534-no/IMG_1157.JPG https://lh3.googleusercontent.com/-ggk5QQcCVe0/VDcV0KtF4gI/AAAAAAAABlc/uZIyqxiepZ8/w399-h534-no/IMG_1158.JPG https://lh6.googleusercontent.com/-HPC6vBQ8UJM/VDcV1VSzw3I/AAAAAAAABlk/bAE2v6mgmYE/w399-h534-no/IMG_1159.JPG https://lh6.googleusercontent.com/-jewsbf-jEwU/VDcWC5J1-HI/AAAAAAAABls/fzpwpUYVChU/w715-h534-no/IMG_1160.JPG https://lh3.googleusercontent.com/-JArpqCE7McQ/VDcWF82CtXI/AAAAAAAABl4/jDUlEjAEMRM/w715-h534-no/IMG_1161.JPG https://lh6.googleusercontent.com/-hgKVwepqZgA/VDcWFPuIL1I/AAAAAAAABl8/hVfXNVVnlfE/w715-h534-no/IMG_1162.JPG https://lh5.googleusercontent.com/-8ZZoUBiSNlc/VDcWNp_tVGI/AAAAAAAABmE/5Q252OBKcL8/w399-h534-no/IMG_1163.JPG https://lh4.googleusercontent.com/-i1mORK3VS0w/VDcWO2WbcGI/AAAAAAAABmM/Ivd3Nm8lAfU/w399-h534-no/IMG_1164.JPG distinct lack of space at the moment with parallel projects ! hope they help someone Looks good Si, nope sorry no solidworks 2014 here, but thanks for the offer. Waiting for my connectors to arrive to wire between the steppers and the cnc driver housing. The plan is to use standard same length leads so they can be all rolled up and just plugged in either end when I assemble and disassmble it. that will also allow me to use the same driver housing if I ever get round to doing the mill / lathe. http://i.ebayimg.com/00/s/MTEwMFgxMTAw/z/HLIAAMXQWzNScq77/$T2eC16J,!zgFIdT9g223BScq77eHdQ~~60_57.JPG Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 10, 2014 Share Posted October 10, 2014 I like those connectors Rob, think I'll get some of those as well (are these the ones? http://www.ebay.co.uk/itm/190952223828 ). Also I like the idea of using a bit of belt under the end of the belt, I'd been going to machine something but your solution is far better and quicker, I'll probably use a plate over the top rather than a bolt through the belt though so I can tension it easier. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 10, 2014 Share Posted October 10, 2014 ...... Apart from a mechanism of attaching the torch, it's fairly complete! Just need to get a quote for cutting & folding all the bits! ..... Will be interesting to see what sort of price this comes out at, there isn't really a budget plasma table available PS Cable ties seem to feature quite often in the torch holding designs! PPS What are your ideas for cable management? Dangled from above? Quote Link to comment Share on other sites More sharing options...
robertspark Posted October 10, 2014 Author Share Posted October 10, 2014 Connectors -> yes those are them from that seller. I must admit the bolt over the top is not the best idea (I have a couple of small plates too not fitted yet), and the belt tension does concern me in operation (I may add a spring to one side so as to have it in tension always). Cable management -> my idea (may not work) is over the top, suspended from above, using a long rod (say 8mm [or 6mm]) with a shepherds crook on the end of it, the idea is that the long rod will flex as the carriages move so that the cable can move somewhat following the carriages slightly (if that makes sense). The reason is to avoid / minimise the cable weight on the carriages and any twist applied to the carriages with the cable weight from the plasma torch. The other advantage is with my 1500 x 1500 table (about 1300 sq usable, so 1/2 sheet size) is that I can assemble everything and just plug the connectors in, cable tie the torch on (cheap ties + disposable + strong), and drape the cables over the shepherds crook in a few minutes, square all the joints up on the frame and tighten in position, square the carriages up and I should be good to go... that's the theory anyway. Looked at the plastic cable management chain, but it seemed a little expensive, and it was not clear what it would run along (normally there is a parallel basket for it to fold and unfold in), also adds to the bulk of the portable / foldaway solution + fragile. then there is the non / semi flexibility of the plasma hose / cable to consider too. Not good with fragile, if I can cut it weld it, drill it and hammer it, it should provide the robustness for it to be disassembled and stored away below the rafters, and latter assembled without a bit of plastic breaking off or being crushed. I'll get some pictures of the drives in an old PC case (power supply is useful for the low voltage (non-stepper drive) stuff. Must admit the limit / home switches are getting me at the moment and integration without loss of table travel. Quote Link to comment Share on other sites More sharing options...
simonr Posted October 10, 2014 Share Posted October 10, 2014 As above, I'd imagined using a shepherds crook attached to one corner of the machine - simple and cheap! I hardly use the limit switches on my lathe or mill - so I don't think they are necessary. You just make sure you set the origin appropriately at the start of the job! On my Mill, I used XLR connectors: http://en.wikipedia.org/wiki/XLR_connector Which are available in up to 7 pin (plus earth through the casing) - and relatively inexpensive. For the different axis, I've just used different numbers of pins in the connectors so they are not interchangeable by mistake. They have stood up to repeated connecting & disconnecting, particularly on my 4th Axis and have stood up well to swarf and coolant. RobertSpark - where did you get the nylon V groove pulleys shown here: The ones I've found seem unduly expensive! si Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 10, 2014 Share Posted October 10, 2014 Probably better to stick with an adaption to fit a hand torch. A straight torch just adds expense I guess. ..... Just had a thought, if you stick with the hand torch and the idea that you can rest the whole framework on the sheet you are cutting you may have a reduced cutting area due to the torch handle hitting the frame. Quote Link to comment Share on other sites More sharing options...
simonr Posted October 10, 2014 Share Posted October 10, 2014 Just had a thought, if you stick with the hand torch and the idea that you can rest the whole framework on the sheet you are cutting you may have a reduced cutting area due to the torch handle hitting the frame. You're right - but I can't see a way around that, other than make the rig bigger! This configuration gives 600 x 700mm. The box section sides are 875mm long and the end sections 1m. A straight torch would give you 660 x 700mm. Either way it gives you about 2 foot square. However, even with a 2' square, since I intend it to sit on top of the sheet, possibly clamped to it, if you cut a number of reference holes, you can use this to move the cutter to the next square along. You could possibly even bolt it to the last reference holes, or just use one to set the origin for the next cut. That way, you could cut an 8 x 4' sheet in 8 moves etc. This is my thought on a universal torch mounting: Either using cable ties or U bolts to secure. It will cope with any angle between the handle from 90 deg to straight. Mine is about 30 deg. Si Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted October 11, 2014 Share Posted October 11, 2014 If your going to sit it on top of the sheet how are you going to support the sheet so the flame can go through but the sheet stays flat? Quote Link to comment Share on other sites More sharing options...
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