Here is a list of all the postings mike mcdermid has made in our forums. Click on a thread name to jump to the thread.
Thread: Tig Welding |
23/07/2013 21:01:58 |
One thing i forgot to ask you mentioned sheet? are you using clad sheet ,that is horrific unless you clean it back to the base metal ,also another tip get a wire brush (stainles) and dedicate its life to cleaning aluminium dont use it on anything else |
23/07/2013 20:53:18 |
Hi rebekah Dont be depressed at all with it its just a case of learning to use what you have. Also give yourself a pat on the back theres nothing like jumping in there and giving what a lot of people think is the hardest material to join a go straight from the off, I learned from some very good welders who used miller and hobart dial arcs, theres no fancy pulse or ac balance control on those machines which date back to the 70s and they make me look like im messing about at it. Pulse is something you can learn with your foot rather than letting the machine do it its a rythm thing ,but one other thing is its easier for it all to slot into place if you see someone do it after an hour it all gels When i was learning it was a 12" squre plate 3mm thick and all i did was run beads of weld to learn the process and adjust setting's, find out out what each nob, did and how it affected the bead of weld width penetration heat soak etc tungsten angles affect things like penetration and bead width also im pretty sure out the box with a machine set at 100hz and 50/50 balance your can get a good solid weld out of it on flat plate go from there learning what each difference in setting does It gets very complicated when you are starting out with so many lights nobs and buttons |
22/07/2013 15:09:06 |
what do you mean the tungsten is burning back At low amps as you describe there should be no danger of this even a 1mm tungsten should be good for 60 amps plus a bit you shouldnt be above 35 amps asa start for what your joining a good rule of thumb is 1 amp per thousandths of an inch up to 1/4" thick and 1.5 amps per thou thereafter we join steel in the 0.6mm to 6.35mm thick range daily and readily 0.9mm wall tube gets welded to 6.35 plate and thicker with no problems whatsoever but i spent years on a miller syncrowave welding thinwall bicycle frames together 1mm sheet is quite thick in my world do you have a footpedal? and understand frequency control for the AC higher means a tighter arc and less wander but it also means your mre likely to penetrate through
tungsten grind angle you might want to try greater than 30 degrees for less penetration IME pulse welding aluminium is very hit and miss you are much better using freq and foot pedal you max amps will be set on the machine and that is what you have on tap at the pedal, no more Using pulse means you have to take into account your on, off time and account for that if you are welding 30 amps peak for 0.2 seconds you dont have a chance of starting a bead you need to go up on your peak amp to near 90 amps the one honest to god true thing i will tell you when it comes to welding thin material is you do get what you pay for with a more expensive welder that goes down to 3 amps ,sure many will say 3 amps is the lowest they will go but when you compare arc stability side by side of a high end machine to a an adequate far eatern machine you see the difference |
Thread: Wood's Metal/Cerrobend suppliers? |
06/06/2013 23:18:54 |
http://www.bendalloy.co.uk
i get mine from him just down t road they do a polybend which is plastic but many other LMAs Edited By mike mcdermid on 06/06/2013 23:19:33 |
Thread: Defective Gearbox/Crank assembly |
09/03/2013 22:00:08 |
which attached model?
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Thread: Drawing Standards |
08/02/2013 22:40:55 |
Jeff daymans sentiments are quite accurate "garbage faster"
I was trained on a drawing board so was taught the art of understanding the need to convey information Cad systems which i have used most of them Solidworks Inventor Pro E NX and Catia allow you to create 3d models and the drawing is just an afterthought IMHO Its only recently there is no need for a drawing anymore ,the digital model is king in some larger institutions where asme y is making inroads ,However they missed the fact that a machinist likes to have a drawing pinned somewhere near a machine and it isnt going away as quick as they thought it would As for BS whatever im sure it used to mean "British Standard" not standard which we will work around to suit everyone and their company's way of doing things hence there is a lack of standard BS8888 is certainly a hotchpotch of differing requirements for the europeans rather than the British However you can get the kids to work to a standard if its set up Solidworks certainly allows you to define BS308 Or BS8888 and automatically draft a drawing using that however as the digital model is dumb when it comes to actually recognising what you put into it in referance to tolerances etc (PRO e is the exception here it wont actually let you define something that is at geometric odds with each other),wether the kid in front of it understands what geometric tolerance or even basic drafting projection is without googling it is a completely different matter
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Thread: Is it possible to still "buy British" ? |
20/01/2013 21:51:09 |
Its not difficult to make something here for a similar price to an import, we have proved that in another industry i work in the problem is, is it worth it? and secondly do you have the time to spend seeking out the skills required to do it ,we researched building UK lathes and found those skills and experience were on the decline I now know from experience we seem to have forgotten how to make things The general number of people that would buy such a hobby or light duty machine is too small to consider it commercially as above we still have sheet metal bashers but boy it aint cheap
Edited By mike mcdermid on 20/01/2013 21:58:20 Edited By mike mcdermid on 20/01/2013 22:00:56 |
Thread: myford super 7 clutch |
20/01/2013 21:43:55 |
there is a chap in leeds now regrinding myfords
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Thread: delcam help |
05/10/2012 19:31:50 |
Jim a lot of stuff delcam do is based on vouchers ,the company i used to work for licensed the translator but before, just as you said Delcam used to make it so that if you wanted a catia file to be used in powermill you could do that but had to run it through exchange and it would also output the catia file as native they called it "exchange' However most models or files in educational versions of software cannot be opened by the full commercially licensed programs for example if i were to try and pen a file created in the educational version of PROe or Creo it will tell me the file type is not supported, similar with solidworks ,there is no way round this unless "you know what to amend in a txt editor" they expect you to buy a full 4-5k worth of software so delcam saying the good projects you want to use "commercially" it will cost 34 quid is a good-ish deal imho. |
Thread: Digital subscription |
04/10/2012 22:25:13 |
i did just that |
04/10/2012 22:25:12 |
i did just that |
04/10/2012 21:35:31 |
I would like to read the lathe review in a previous issue of MEW if you subscribe are you able to access a previous issue? or only issues from your subscription date moving forward? |
Thread: Myford Super 7 |
04/10/2012 21:14:34 |
mines the same as mikes and has the noisy needle rollers Ive kind of learned to love the rythm they make as they go round |
Thread: Myford ML7 leadscrew |
04/10/2012 21:09:07 |
Kingston engineering sell leadscrew in hull £56 for mine and i just machined the ends to spec |
Thread: delcam help |
04/10/2012 21:02:14 |
If you can use SW you will be ok with the delcam product download the manual or a tutorial what you want to do will be very similar to SW just behind a different icon or workflow,I switch between SW Catia Unigraphics and Pro E for Cad and powermill and mastercam for Cam they pretty much all do exactly the same thing and once you learn the location of the button that does the similar thing in SW it makes sense Its just a case of finding out where |
Thread: Mach3 |
28/09/2012 15:54:56 |
Posted by Tony Jeffree on 28/09/2012 10:10:10:
Isn't the whole discussion of whether or not John M's jointing technique is new or old rather missing the point? The important point (to me, at least) is that he is using techniques that I haven't seen described in MEW before, and seeing what he has done is already causing ideas to spark in my brain. Laser cutting is getting more and more accessible to the model engineer - either as a bought-in service or if you want to go the whole hog, the entry price for a small laser cutter is comparable to that of a small CNC mill. Admittedly, you would pay more to buy a laser cutter capable of cutting sheet steel, but as demonstrated with the wooden CNC mill a couple of issues ago, there's a lot that can be done with other materials (wood, perspex...) as the starting point, and even a small laser cutter will handle those materials to a reasonable thickness. Combining the accuracy of laser cutting with the kind of easy-to-assemble jointing systems John M is using is very interesting. With free software available for CAD, the idea of shipping a set of drawings to your local friendly laser cutting house & getting back a kit of parts for your machine is very appealing indeed, and as John M indicates, the premium over the cost of material isn't outrageous either. Regards, Tony Sorry it might be my post that came across as not a new trick in the book, not really ,my intention was to point out that a certain jet engine company are using the same jointing and construction method to make mich lighter jigs and fixtures , not made out of solid billets etc and are cheaper in the traditional toolmaking sense materials wise, these things are holding micron repeatability ,they have invested considerable amounts of money in proving this works and its used in production, its a very effective method the sticky for me was when the development guy at RR was saying patent this that and blah blah and the two guys next to me pointed out this wasn't new and that several companies had done this before those reprap or is it makerbot? also use this principle but this is the way things are headed lots of big companies do light tools (light on material costs or use, not lightweight materials) I read an article once on a division master for thread cutting by the time I had thought it through a stepper ,driver and pc would do the same ,the PC is what im used to but i would do the division master experiment to learn something new I suppose if you come from a world of CNC its nice to just use your brain and hand co-ordination on a manual machine ,if your coming at it as manual guy your also learning something new Folks not used to seeing a machine cut threads are often mouth agape when (tongue in cheak statement) they realise the machine does it all for you.... |
27/09/2012 17:20:30 |
Posted by John McNamara on 27/09/2012 14:55:21:
Hi All This weekend I will be showing a CNC router made from Laser cut 5mm steel with almost no welding, at the Melbourne Model Engineering Exhibition. The machine will be driven by Mach 3 when it is completed. It was designed using Autocad a commercial program however there are many free CAD packages that can generate DXF files to give to a laser cutting service. Almost No Welding? The design uses a joint of my own (well I have never seen it before) A design that is effectively (two) mortise and tenon pairs together with standard fasteners between the pairs, to make each connection) ; in this case M5 high tensile nuts and bolts, to join the various members together. Using this method there are zero sheer forces on the fastenings only tension forces. I believe it could easily be scaled up to at least 12mm plate. Laser cutting has very little undercut; however there is some..... to counter this make sure the attached plates are interlocked in sets of 3 opposed at 90 degrees. Buy doing this using my best More and Wright square to test the joints I could see no light. bolt holes aligned so perfectly that there was no eye observable misalignment. There are no tapped holes in the plates. The bolts and nuts fit in slots you can see the slots in the views. If you are wondering the only welds are the end plates of the 75mm sq tube rail supports, We are going to make a new machine with joined 5mm plate instead of these tubes. It will be more accurate and lessen the packing we needed to set the rails true on the RHS (we used a surface plate). Laser cutting is now a fairly competitive area and the group was able to negotiate a reasonable cost for the work roughly steel cost plus steel cost x 2 for labour. The parts came back accurate to .01mm accuracy. we allowed on top of that .1mm (point one) clearance for the joints and no allowance for holes. When the parts came back form the cutting service there were small (tiny) dags here and there. about 2 hours work total with small file to clean all the joints and it went together like a clock. No welding distortion...... We redrilled all the round 5mm holes to clean them out as they were already laser cut it only took a few seconds per hole. the holes were positioned far better than I can do with a centre punch. Yes the machine could have been made by hand methods but have a look at the parts photo. how many hundred man hours. I have spent a fair number of hours just turning all the rotating parts . The machine also uses Chinese round shaft linear rails and a z axis ball screw. You will be amazed how the cost of these have fallen on EBay and the like. X and y drives are 5mm timing belt. All the rotating parts use flanged ball bearings 8mm and 12mm again the internet provided a source VXB Bearings were very helpful and are a good starting point. The flange is clamped between the frame and a laser cut plate with 4 M4 bolts I have uploaded five CAD file images into an album at this site: 2 examples below. The carriage is now completed and next week a stand will be constructed. Next week I will upload a set of photos. The design is a collaboration with a great friend Leo S and The Bright Men's shed group, Bright is a central Victorian country town. A Men's Shed is a community supported building equipped with various metalworking, welding and wood working machinery; members pay a nominal fee to pay for tea and coffee. and are free to use the equipment (after doing OH&S induction and training). New technology to me definitely has a part in model engineering. Cheers John Edited By John McNamara on 27/09/2012 15:17:14
John I see this method of construction every day, Rolls Royce use it for very accurate very repeatable (read 1 to 5 micron) jigs and fixtures for turbine blades ,both grown and forged machined ,laser cut on a machine which even I couldnt believe would repeatably cut to the tolerances they claimed,Turns out MAZAK made the machine an example for their demonstrations and it does hold what it says on the tin Unfortunately despite the claims of PATENTS etc in the way things are done etc it was recently pointed out to them that a company in halifax in the UK have been putting huge industrial fans together this way for the best part of 20 years |
Thread: where will the next generation of engineers come from |
25/09/2012 19:47:47 |
Some interesting views on the subject from you all Im from the playstation generation which prompted my question, I was luck enough to have worked through college etc and gone through the mill with regards apprenticeships (a hollow promise about the time British aerospace went west) I work in a facility that does lots of government funded development in machining ,mori seiki have all their happy little visitors to see the cutting edge of adaptive machining etc ad nauseum We specialise in ALM or growing bits and as someone pointed out earlier The limitations of what we can do is actually the CAD software and computational power available ,not the thought process of machining from solid metals are being rplaced by composites on an almost daily basis However this was not my point i think I read a book which touched on things i havent used for 15-20 years and it made me wonder that even in a place where its often described as the bleeding edge of technology I still have to think back to old ways of solving a problem or what the foundations or origins of where the new technology has come from Will this ability to have a thought process as opposed to produce something automatically and not understand where it originated end with my generation or will it just be replaced by another in another 100 years time? ,if progress is to believed the myford I love to fiddle with will be looked upon like the discovery of mankinds first cutting tools or even a sharpened flint. I find it sad that a book which to me has been a learning tool has brought these thoughts into play especially as its the book which is now considered a dinosaur |
25/09/2012 19:47:46 |
Some interesting views on the subject from you all Im from the playstation generation which prompted my question, I was luck enough to have worked through college etc and gone through the mill with regards apprenticeships (a hollow promise about the time British aerospace went west) I work in a facility that does lots of government funded development in machining ,mori seiki have all their happy little visitors to see the cutting edge of adaptive machining etc ad nauseum We specialise in ALM or growing bits and as someone pointed out earlier The limitations of what we can do is actually the CAD software and computational power available ,not the thought process of machining from solid metals are being rplaced by composites on an almost daily basis However this was not my point i think I read a book which touched on things i havent used for 15-20 years and it made me wonder that even in a place where its often described as the bleeding edge of technology I still have to think back to old ways of solving a problem or what the foundations or origins of where the new technology has come from Will this ability to have a thought process as opposed to produce something automatically and not understand where it originated end with my generation or will it just be replaced by another in another 100 years time? ,if progress is to believed the myford I love to fiddle with will be looked upon like the discovery of mankinds first cutting tools or even a sharpened flint. I find it sad that a book which to me has been a learning tool has brought these thoughts into play especially as its the book which is now considered a dinosaur |
22/09/2012 20:44:13 |
I was reading the George H Thomas book recentley, my question of where the next generation of engineers or thinkers even will come from.What will the next generation of digital documents contain? |
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