JeffP Posted February 22, 2013 Author Share Posted February 22, 2013 I'd not thought of that.......maybe buy a 5/32 drill and a taper reamer? That's ANOTHER tool and another £7-8 to find. When using a taper reamer, do we use it from both sides, so as not to produce a tapered hole? Link to post Share on other sites More sharing options...
Miss Prism Posted February 22, 2013 Share Posted February 22, 2013 I'm not in 7mm, but I find it difficult to see how any self-respecting 7mm loco builder could get by without 3/16" parallel and 1:50 taper pin reamers. Not cheap, admittedly. Having said that, some 3/16" round bushes I checked today were nearly 10 thou overbore and some Slaters axles I checked today were 3 thou undersize, so any precision tooling would be wasted on that kind of rubbish. Link to post Share on other sites More sharing options...
ozzyo Posted February 22, 2013 Share Posted February 22, 2013 Hello JeffP, as your wanting to produce your own bearings, it sounds like you have a lathe to do the job on? Most of the time a drill will produce a hole of a slightly bigger size then the drill so a 3/16" drill will produce a hole of approx. 4.8mm about the right size for us. i would not use a tapered reamer to open out a bearing as it will produce a twin sided taper to the bearing hole. I do do something similar to this but only in the up and down directions. OzzyO. Link to post Share on other sites More sharing options...
RMweb Gold ngtrains.com Posted February 22, 2013 RMweb Gold Share Posted February 22, 2013 I'm not in 7mm, but I find it difficult to see how any self-respecting 7mm loco builder could get by without 3/16" parallel and 1:50 taper pin reamers I haven't got as far as owning taper pin reamers. What size is recommended Link to post Share on other sites More sharing options...
ozzyo Posted February 22, 2013 Share Posted February 22, 2013 I'm not in 7mm, but I find it difficult to see how any self-respecting 7mm loco builder could get by without 3/16" parallel and 1:50 taper pin reamers. Not cheap, admittedly. Having said that, some 3/16" round bushes I checked today were nearly 10 thou overbore and some Slaters axles I checked today were 3 thou undersize, so any precision tooling would be wasted on that kind of rubbish. Hello Miss P., I'm a bit in to the 7mm game, and I've never had one that has been over size by 10thou". over size by 0.01mm yes (over size by 0.004"). The same with the axles, if the axle was 0.003" under size how? As this is not to any metal stock size that is made. If you think about it all the axles that Slater's make will be produced from standard metal stock so if any had been made from under size stock I think that it would have been noticed by now. As to the 1:50 taper pin reamer "why"? I have a 1:64 taper pin reamer if I have to move the taper pins in a set of Alan Harris wheels. If your going to check any size always reset your calliper to zero and then do the measurement. OzzyO. Link to post Share on other sites More sharing options...
Miss Prism Posted February 22, 2013 Share Posted February 22, 2013 Hi Ozzyo On the axle diameter, my measurement was a very quick diameter check with a digital caliper, which might not have been reading quite right, so I could re-check with a micrometer to get a better value. My view however is that I would expect ground or silver-steel stock to have a diameter not less than 0.001" below the nominal diameter. I wasn't impressed by the surface of the Slater's axles btw. As for the taper pin reamer, I mentioned '1:50' only to distinguish it from a coarse taper reamer, which is what some people incorrectly perceive to be a taper pin reamer. A 1:64 is even better for our purposes. I use mine (2mm and 1/8" varieties) to produce compression fits between axle and plastic wheel centres and have even managed to produce a metal-to-metal interference fit, which is probably in the region of 0.00025". But maybe 7mm is a foreign country, they do things differently there. Link to post Share on other sites More sharing options...
N15class Posted February 22, 2013 Share Posted February 22, 2013 I'd not thought of that.......maybe buy a 5/32 drill and a taper reamer? That's ANOTHER tool and another £7-8 to find. When using a taper reamer, do we use it from both sides, so as not to produce a tapered hole? DO NOT use a tapered reamer for bearing holes. I use a 190 thou parrallel one but others on here have said 4.8mm Link to post Share on other sites More sharing options...
PatB Posted February 23, 2013 Share Posted February 23, 2013 Whilst I would agree that a taper reamer probably isn't a great idea for axle bearings (disclaimer: not an experienced loco builder but a professional engineer and general technical fiddler), it's worth pointing out that a 3/16 hand reamer has a lengthy tapered portion ahead of its parallel section. Chinese reamers are very cheap these days. I can (and did, along with other sizes) get a 3/16 for AU$11 so I'd expect to pay no more than a fiver in the UK. I doubt if so cheap a tool will be very durable, but for occasional use in brass or bronze it should be fine. Mine are so far. Link to post Share on other sites More sharing options...
Grasshopper John Posted February 23, 2013 Share Posted February 23, 2013 Sorry if this sounds daft, but why use a tapered reamer at all when you know what you are going to achieve by using a Parallel reamer. I'll get me coat Grasshopper J. Link to post Share on other sites More sharing options...
Miss Prism Posted February 23, 2013 Share Posted February 23, 2013 As PatB says, the front slightly tapered portions of hand reamers can be extremely useful. But we're probably getting somewhat offtopic now. Link to post Share on other sites More sharing options...
Buckjumper Posted February 23, 2013 Share Posted February 23, 2013 In re the slotted square brass bearings - phone Slaters and they'll sell you a bag of however many you need. Back to the reamers - I use a 3/16th parallel reamer to clear the bearings before setting up the frames on my jig. Once the bearings are installed and everything is square, I run a 4.8mm parallel reamer right through the pair of bearings to give a working clearance. Link to post Share on other sites More sharing options...
JeffP Posted February 23, 2013 Author Share Posted February 23, 2013 Yes, I already own a 1/8th and a 3/16th parallel reamer, both cost mucho dinros some years ago, the 1/8th one was £13 in 1980!!! Why do I want a 4.8mm one? And yes, I have access to a lathe, a small Emco compact 5, lots of accessories but not enough tools. It could do with a more accurate 3-jaw chuck, but I keep balking at £150 for something that gets so little use, and I keep meaning to invest in a collet chuck, since I DO have a full set of 25mm collets. I assume I shall be suing the 4-jaw chuck for making bearings from square stock? However, I shall contact Slaters on Monday and get a price for theirs too..... Link to post Share on other sites More sharing options...
Horsetan Posted February 23, 2013 Share Posted February 23, 2013 ...I shall be suing the 4-jaw chuck ..... *looks up County Court Procedure Rules to see if this type of thing is covered.....* Link to post Share on other sites More sharing options...
Buckjumper Posted February 23, 2013 Share Posted February 23, 2013 Why do I want a 4.8mm one? I'm no engineer, but I am a model maker. For years I built locos just using the 3/16" reamer through the bearings and then ran them for hours until they were free-running. If the axles are machined to 3/16" and the bearings reamed to 3/16" , and assuming (!) both processes are accurate it's going to be a bit tight. Several years ago I asked a well-respected modeller how he got his locos running so freely first time out and he said he used a 4.8mm reamer which is a thou or two over 3/16" - essentially he built in the working clearance ("a good running fit"). I think you'll even find the use of a 4.8mm reamer suggested in the latest edition of the G0G manual. Works for me! Link to post Share on other sites More sharing options...
JeffP Posted February 23, 2013 Author Share Posted February 23, 2013 OK, that makes sense. In the meantime, I've checked out 4.8 mm reamers........WOW! £32 each, against £8 or less for a 3/16th one....... And rare as hen's teeth. Link to post Share on other sites More sharing options...
John K Posted February 23, 2013 Share Posted February 23, 2013 Search eBay for a 4.8mm reamer. I think you will find something serviceable and cheaper. Best, John Link to post Share on other sites More sharing options...
JeffP Posted February 23, 2013 Author Share Posted February 23, 2013 That's where I looked: only Chronos listed one, and that £37 brand new. I've saved my search..... Edited: found a taper shank one that would do, especially as it's the same as my lathe, 1MT. So, drill in the lathe, 3/16th, remove drill chuck and arbor, fit reamer, ream in the lathe turning the chuck by hand? Link to post Share on other sites More sharing options...
John K Posted February 23, 2013 Share Posted February 23, 2013 Leave it a few days and a used hand reamer might turn up. I bought one last week for a fiver... ...perfectly good enough for our use. John Link to post Share on other sites More sharing options...
Pebbles Posted February 23, 2013 Share Posted February 23, 2013 Why not make a reamer. Silver steel turned to 4.8mm, file obliquely to a point then temper. After cleaning up hone on a stone. Reamers constructed in this way were described in MRN back in the fifties and also some years ago in MRJ. Link to post Share on other sites More sharing options...
PatB Posted February 24, 2013 Share Posted February 24, 2013 A 3/16 reamer with a bit of fag paper packed into the grooves on one side will cut fractionally bigger than its nominal size. Thirty quid for a 4.8 mm reamer or a few pence for a packet of Rizlas, the choice is yours. Link to post Share on other sites More sharing options...
Adrian Posted February 24, 2013 Share Posted February 24, 2013 I assume I shall be suing the 4-jaw chuck for making bearings from square stock? If you've already got one then it may help but it's quite easy to do with a 3 jaw chuck. Get a length of steel bar, probably something like 3/4" - turn a step along it at least the width of the jaws in your chuck then cut off with a 1/2" collar to it. Now with it reversed the turned section is held in the 3 jaw, drill a clearance hole for the square stock, measured across the diagonal. Finally in the collar drill and tap something like 2BA, this will clamp your square stock in your sleeve sufficient for turning. Link to post Share on other sites More sharing options...
Pebbles Posted February 24, 2013 Share Posted February 24, 2013 As mentioned by Adrian but, mark the tube against a numbered jaw and slit between the numbered and adjacent jaw.When the square bar is inserted and the chuck tighten the square bar will be automatically centralised. Do remember always to keep the mark on the tube aligned with the selected jaw. Link to post Share on other sites More sharing options...
JeffP Posted February 24, 2013 Author Share Posted February 24, 2013 Leave it a few days and a used hand reamer might turn up. I bought one last week for a fiver... ...perfectly good enough for our use. John I've left the search on memory. Hmmmmmmmm, this gets ever more complicated. I should have stuck to the task of finding some ready made. I wonder how many I could buy for the cost of the parting tool, the brass stock, the 4.8mm reamer, .....I'll enquire tomorrow from Slaters and post the result on here. Link to post Share on other sites More sharing options...
3 link Posted February 24, 2013 Share Posted February 24, 2013 This thread reminds me of one of my favourite old songs by Simply Red " Money too tight to mention" . Martyn. Link to post Share on other sites More sharing options...
JeffP Posted February 24, 2013 Author Share Posted February 24, 2013 Unfortunately, I DO have to watch the pennies, so more expenditure has to be justified. Anyone can throw money at a project, but you need to see results if it's to be justified. Ask Labour...... Link to post Share on other sites More sharing options...
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