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Model Forum / General / Models / February 2010Locating pin steel?
I'm upgrading my BCA mill (again) and there are a few locating pins missing. The pins are used to ensure that the bits align accurately when assembled. The pins are 0.1875 (+/- 0.0001) inches, or accurately 3/16, diameter. They are reasonable steel, pretty tough but not hard like eg drill rod or silver steel. Any suggestions what I should use to make new pins, or where I could get it? Need about 6". Thanks, -- Peter Fairbrother > I'm upgrading my BCA mill (again) and there are a few locating pins > missing. The pins are used to ensure that the bits align accurately when [quoted text clipped - 6 lines] > Any suggestions what I should use to make new pins, or where I could get > it? Need about 6". If the pins are shear pins designed to sacrificially break before something more expensive gives way then use something not too strong. If all they do is locate then use anything you like. Off the shelf dowel pins would be as easy as anything I'd imagine or just get a length of 3/16" silver steel or anything else pre-ground to size and cut it up. Once the items are located and bolted down the pins do bugger all. They don't need to be hardened.  SignatureDave Baker >I'm upgrading my BCA mill (again) and there are a few locating pins >missing. The pins are used to ensure that the bits align accurately when [quoted text clipped - 10 lines] > >-- Peter Fairbrother 3/16" silver steel. Chronos; J&L; Cromwell; local supplier... Cut off, face, chamfer or radius ends, as appropriate, If they need to resist marking over time:- cover with well wetted bathroom soap, heat to cherry red, throw in a bowl of water, put in the kitchen oven at 250C for 20 minutes. then polish with fine wet&dry paper or SolvolAutosol Still haven't even started on my Excel model 0. It's got 7/16BSW 14tpi leadscrews :-O Mark Rand RTFM >> I'm upgrading my BCA mill (again) [...] > Still haven't even started on my Excel model 0. It's got 7/16BSW 14tpi > leadscrews :-O I'm not sure what kind of leadscrews my BCA originally had, though they were a sensible 10 tpi with 100 division dials, giving a thou per division. I replaced them with metric ones just after I got it. Not expensive to do, less than £30 apart from the trapezoidal tap (from Marchant Dice, a POS, but the BCA double nut system means the shittiness of the threads it cuts doesn't matter). I used 10 x 2 mm leadscrews 'cos I wanted a 2mm/rev manual feed for sensible dial readings, but I think they are too thin. 12mm would be better, but I couldn't find 12 x 2 mm leadscrews. In the middle of a long CNC conversion now, keeping the same leadscrews, though I'll fit ballscrews someday, most probably. Replaced the spindle with a fixed ER25 straight shank chuck, as a set of BCA collets costs more than a BCA. Made new bronze spindle bearings, but reused the thrust ball bearings. Also fitted a 600W DC motor at the side, rather than at the back, still needs a guard though, and probably a fan too - though I've run it quite hard and had no motor overheating problems. Have an optional 54,000 rpm air spindle too, but haven't done more than test that. Some photos here, ~ 1 MB each: http://www.zenadsl6186.zen.co.uk/mill1.png http://www.zenadsl6186.zen.co.uk/mill2.png -- peter f If you use silver steel and harden it,just be aware it grows slightl when hardened. Alla -- Allan Waterfal >I'm upgrading my BCA mill (again) and there are a few locating pins >missing. The pins are used to ensure that the bits align accurately [quoted text clipped - 10 lines] > >-- Peter Fairbrother Peter, Assuming you don't need the 6" all in one piece but that's the total required, how about: http://www.mscjlindustrial.co.uk/CGI/INPDFF?PMCTLG=00&PMPAGE=1504&PMITEM= MBF-00023J Pity you need imperial rather than metric, I just bought a metric set from them which will probably last me several lifetimes, I could have sent you what you needed. David SignatureDavid Littlewood > I'm upgrading my BCA mill (again) and there are a few locating pins > missing. The pins are used to ensure that the bits align accurately [quoted text clipped - 10 lines] > > -- Peter Fairbrother J&L was mentioned, they also do one option of 3/16" dowel pins http://www.mscjlindustrial.co.uk/EXD-23100K/SEARCH:KEYWORD/product.html .I don't expect you need a 100 but maybe you can find a use for the others. > I'm upgrading my BCA mill (again) and there are a few locating pins > missing. The pins are used to ensure that the bits align accurately when [quoted text clipped - 10 lines] > > -- Peter Fairbrother === Peter, is the 6" you mentioned the total length you need, or for one individual pin? I ask because if they are only short as many locating dowels are, I have used Velocette big-end rollers for similar tasks. These are are available new separately, or used from just about any Velo Fellow! These are 3/16", hardened and accurately ground (well, they were, whem new!). JW² === Thanks all, but maybe I wasn't clear - there are two types of pins ont' mill, one type is hardened and one isn't. It's very easy to tell the difference. It's the non-hardened ones I was looking for. I haven't a clue why they aren't hardened, but they surely aren't. Tough, good-looking steel most definitely, and very accurate as to diameter - but not hardened. Anyway, I turned up a bit of scrap bronze and that seems to work fine. Thanks again all, learned something for later, -- Peter Fairbrother >Thanks all, but maybe I wasn't clear - there are two types of pins ont' >mill, one type is hardened and one isn't. It's very easy to tell the [quoted text clipped - 7 lines] > >Thanks again all, learned something for later, OK, didn't realise this. Bit late (for this time) but you could perhaps have used PGMS. Are the non-hardened ones shear pins? If so, you really don't want anything too tough. David SignatureDavid Littlewood >> Thanks all, but maybe I wasn't clear - there are two types of pins >> ont' mill, one type is hardened and one isn't. It's very easy to tell [quoted text clipped - 11 lines] > OK, didn't realise this. Bit late (for this time) but you could perhaps > have used PGMS. What's that? Precision ground mild steel? Is it easy to get hold of? Are the non-hardened ones shear pins? If so, you really > don't want anything too tough. I don't think they are shear pins, just locating pins - I think they are unhardened because they are going into cast iron on both ends. At any rate all the pins going from cast iron to steel are all hardened, and the ones going from cast iron to cast iron aren't. -- Peter Fairbrother > David >>> Thanks all, but maybe I wasn't clear - there are two types of pins >>> ont' mill, one type is hardened and one isn't. It's very easy to [quoted text clipped - 25 lines] >> >> David Manufacturers preference maybe, I helped a mate dismantle a Hayes Diemaster mill recently and partly re-assemble it (it's in the process of being checked out and cleaned up). The dowels pins between the column and base, CI to CI, are hardened. I was surprised that although the tops of the dowel pins were radiused, as I would expect is common, the bottom end was square and almost sharp and the mating holes for the pins in the base casting had no chamfer. The dowel pins I'm used to have a taper on one end, to aid alignment I suspect, and domed on top. >> OK, didn't realise this. Bit late (for this time) but you could >>perhaps have used PGMS. > >What's that? Precision ground mild steel? Is it easy to get hold of? Yes; and yes. I usually keep a modest stock of 5-6 standard sizes, including 3/16 - I used a bit last night to make a dummy 0-gauge axle (3/16 is the standard size for that). Think I got it from Mallard Metals - not on their web catalogue, but if you ring them up and ask them they usually have it in stock. http://www.mallardmetals.co.uk/products_and_services.htm >Are the non-hardened ones shear pins? If so, you really >> don't want anything too tough. [quoted text clipped - 3 lines] >any rate all the pins going from cast iron to steel are all hardened, >and the ones going from cast iron to cast iron aren't. Can't imagine it would create a problem using hardened ones for this, unless the hole was tight and there was a risk of splitting the iron (in which case it would apply to the other sort as well!). David SignatureDavid Littlewood >I'm upgrading my BCA mill (again) and there are a few locating pins >missing. The pins are used to ensure that the bits align accurately [quoted text clipped - 6 lines] >Any suggestions what I should use to make new pins, or where I could >get it? Need about 6". Peter, An afterthought, but by coincidence I just found this supplier of precision ground 303 stainless steel in small quantities: http://www.motionco.co.uk/shafts-c-29.html The 3/16" is +0.000/-0.0014" May not be of use to you, but others might find it of interest. David SignatureDavid Littlewood |
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