97xx Posted January 28, 2021 Share Posted January 28, 2021 (edited) Just to prove I'm not making this up. First picture, top to bottom: Taper reamer - horrid tool (probably came free with something. Never used - no swarf!) Hand reamer (e.g. drill a 6.8mm hole and ream out to 7mm precisely) Adjustable hand reamer (where you don't want an standard size) Cutting broach Smoothing broach A machine reamer has straight flutes versus spiral ones of a hand reamer - so it doesn't get drawn in (and break off...), Second picture - many broaches. Top ones very big clock or 'railway', the bottom ones small watch and are vanishingly small! Edited January 28, 2021 by 97xx Added machine reamer comment Link to post Share on other sites More sharing options...
97xx Posted January 28, 2021 Share Posted January 28, 2021 (edited) And as Jeff referred to keyway broaches, found this - as I haven't got any. The cylindrical insert goes in a hole and the tapered broach with the hard teeth cuts the keyway in the material surrounding the hole on the out stroke. This set (4, 5, 6, 8mm) is about £500... Edited January 28, 2021 by 97xx Link to post Share on other sites More sharing options...
Jeff Smith Posted January 28, 2021 Share Posted January 28, 2021 (edited) My engineering workshop practice is light to medium machining and hand fitting so I bow to your watch making knowledge. However Wikipedia describes a broach as a linear tool, ie, pushed in or pulled out on a machine. Edited January 28, 2021 by Jeff Smith Link to post Share on other sites More sharing options...
97xx Posted January 28, 2021 Share Posted January 28, 2021 33 minutes ago, Jeff Smith said: My engineering workshop practice is light to medium machining and hand fitting so I bow to your watch making knowledge. However Wikipedia describes a broach as a linear tool, ie, pushed in or pulled out on a machine. I'd only ever known broaching as keyway work until I got into watches/clocks too. Well, and rotary broaching for making 'square holes' which I really fancy trying but have only ever resorted to milling, filling and turning to do thus to which you'll know what I'm getting at. 1 Link to post Share on other sites More sharing options...
PenrithBeacon Posted January 28, 2021 Share Posted January 28, 2021 A taper reamer is used to cut a tapered hole for a tapered pin; it isn't related to a broach which is a tool used by clockmakers/watchmakers to open out holes to an exact size. In a professional engineering workshop a broach wouldn't be used to create a bearing, which is exactly what a crankpin hole in a coupling or connecting rod is. 1 Link to post Share on other sites More sharing options...
97xx Posted January 28, 2021 Share Posted January 28, 2021 (edited) Aside all the details, cutting broaches are absolutely brilliant for easing holes in our scales, especialy with etches which always seem to need it. Brake shoe rod holes etc etc. Gentle, progressive, sharp and concentric. Seriously for rods ends they work brilliantly down at that 1-1.5mm size. Edited January 28, 2021 by 97xx 1 Link to post Share on other sites More sharing options...
97xx Posted January 28, 2021 Share Posted January 28, 2021 (edited) 11 minutes ago, PenrithBeacon said: A taper reamer is used to cut a tapered hole for a tapered pin; it isn't related to a broach which is a tool used by clockmakers/watchmakers to open out holes to an exact size. In a professional engineering workshop a broach wouldn't be used to create a bearing, which is exactly what a crankpin hole in a coupling or connecting rod is. However, I would say that a broached crankpin hole (cut and smoothed) at 4mm scale is actually an almost perfect application for the process? Yes, for an axle I would ream it every time - different intent. Edited January 28, 2021 by 97xx 1 Link to post Share on other sites More sharing options...
Miss Prism Posted January 28, 2021 Share Posted January 28, 2021 I agree with 97xx that coarse-taper reamers (as in the OP) aren't much good for our use. However, 1:48 or 1:50 taper reamers are fantastic for wheel fitting and bearing nudging. Prices are eye-watering, although Tracy Tools did a cheap one suitable for the 1/8" window. Not sure if they still have them. 1 Link to post Share on other sites More sharing options...
RMweb Premium NFWEM57 Posted January 29, 2021 Author RMweb Premium Share Posted January 29, 2021 I have found the discussion on reamers and broaches really interesting and informative. I have two sets of 6 cutting broaches bought off Amazon, 0.4~1.4 mm and 1.2~3mm. Might be worth me getting a set of matching smoothing broaches as well. Had a quick search of the internet and found the following. Squires Tools catalogue http://www.squirestools.com/files/20-06A Files & BroachesWEB.pdf shows various cutting /smoothing broaches and parallel / tapered reamers. The 1/8th inch parallel taper is £29.99 and I suppose if you are making a lot of chassis, worth the investment. Cromwell tools have a taper pin reamer nominal 1.5mm which has a minimum of 1.4mm and a maximum of 2.4mm over a flute length of 37mm. https://www.cromwell.co.uk/shop/cutting-tools/hss-taper-pin-reamers/1-50mm-hss-s-s-st-fl-hand-taper-pin-reamer/p/SHR0652800A Not cheap at £46.49 but looks far more robust than the broaches I am using. It occurred to me that for the thickness of the coupling rod, 1.1mm, the taper would only be 0.03mm (1.20 thou). So, I might invest in one given that is looks far sturdier. Regards, Patrick Link to post Share on other sites More sharing options...
Jeff Smith Posted January 29, 2021 Share Posted January 29, 2021 (edited) Might be more prudent to just buy good quality small drill bits. With a metric set and an imperial set you will cover most requirements. Coupling and connecting rods need about 5 thou of play anyway. For etched chassis I open up with a course taper reamer until the top hat bearing just fits then solder in position. Edited January 29, 2021 by Jeff Smith Additional comments Link to post Share on other sites More sharing options...
RMweb Premium Siberian Snooper Posted January 29, 2021 RMweb Premium Share Posted January 29, 2021 I find drills in 10 or 15 thou brass or N/S small parts can wreak havoc with them, I messed up a set of coupling rods try to drill them, now I only use broaches for such items. Link to post Share on other sites More sharing options...
Jeff Smith Posted January 29, 2021 Share Posted January 29, 2021 You have to increase drill size gradually with a hand pin vice...... Link to post Share on other sites More sharing options...
RMweb Premium NFWEM57 Posted January 30, 2021 Author RMweb Premium Share Posted January 30, 2021 4 hours ago, Jeff Smith said: You have to increase drill size gradually with a hand pin vice...... Problem in UK is where to buy good quality miniature drill bits. Tried the PCB ones, easy to snap if not used in a drill press and expensive. Best ones so far came from screwfix; HSS 1mm, 1.5mm only though. But pretty strong and effective. Also, Proxxon HSS micro drills good. Link to post Share on other sites More sharing options...
Jeff Smith Posted January 30, 2021 Share Posted January 30, 2021 These will not be top quality but ok for occasional use https://www.ebay.com/itm/0-3-1-6mm-Miniature-Bit-20-Pcs-Set-HSS-High-Speed-Steel-Twist-Drill-Bit-Set-Tool/362595835849?hash=item546c655fc9:g:TAAAAOSw96FcgNpP&redirect=mobile Link to post Share on other sites More sharing options...
RMweb Premium NFWEM57 Posted January 30, 2021 Author RMweb Premium Share Posted January 30, 2021 4 minutes ago, Jeff Smith said: These will not be top quality but ok for occasional use https://www.ebay.com/itm/0-3-1-6mm-Miniature-Bit-20-Pcs-Set-HSS-High-Speed-Steel-Twist-Drill-Bit-Set-Tool/362595835849?hash=item546c655fc9:g:TAAAAOSw96FcgNpP&redirect=mobile Jeff, Thank you. Have similar from Axminister tools as well as the ones you showed. The Axminster tools pack much sharper. https://www.axminstertools.com/11-piece-micro-drill-set-610188 Pat Link to post Share on other sites More sharing options...
PenrithBeacon Posted January 30, 2021 Share Posted January 30, 2021 The pack from Eileens and Squires seem to be much the same. In my experience they are OK for drilling plastic but not for brass/nickel silver. I have started buying drills from Macc Models, they are more expensive but better. Link to post Share on other sites More sharing options...
97xx Posted January 30, 2021 Share Posted January 30, 2021 On 29/01/2021 at 20:04, Siberian Snooper said: I find drills in 10 or 15 thou brass or N/S small parts can wreak havoc with them, I messed up a set of coupling rods try to drill them, now I only use broaches for such items. Wise words. Drills and thin material are generally to be avoided as you will tend to get a triangular hole. In bigger sizes you can grind the bits to have a 'lip and spur' which means that the central spur centres and then the lips cut a circle before the body of the drill removes material. However, impossible to grind below about 3-4mm. Many wood drills are ground this way and you can use these in brass or N/S sheet if they're reasonable quality. 1 1 Link to post Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now