I was wondering if a step drill (13mm max diameter) would be a better idea for enlarging as it would be self centering?
I think you'll be fine, what may happen is you get chatter from the drill so may end up with the not so perfect edge.
Also you don't really need to buy proper counter bores, the right size drill bit used in the same way works great for pretty much the same effect, do you really need need flat bottom holes for the cap head to live in?
The timing is good on this one because I'm currently in the process of doing the same myself, stepping up in size, cheap drill press, simular sizes being dealt with, here's some pics:
I'm stepping up to 15.5 and 20mm for the screw clearance hole (the very middle one) :). I can show the bigger holes if you really want but they came out pretty decent, don't use a step drill and if you don't mind go for quality drill bits.
If you do end up with a less desirable finish on the bore OD, you can always add a chamfer with a counter sink or again an over sized drill bit.
Edit: Just to add, I prefer to go with Dormer for drills and taps after using them after cheap crap and the difference is night and day, however even on eBay Dormer comes at a price, check out Osborn/Warwick/Heller/Goliath, look up Steve (cncpoorboy) on eBay he's got some smashing deals for what what looks to be old new stock, new stock and the stock is all those shiny metal things we're so attracted to.
Last edited by Lee Roberts; 05-02-2016 at 08:03 PM..Me
An m12 counterbore will cost the same if not less than the equivalent bit, so I would do the job properly... http://www.arceurotrade.co.uk/Catalo...k-Counterbores
Define properly, plus a counterbore only dose one job, a drill offers you more options/value if you don't mind being a little creative with it.
Not getting into right or wrong as I think it's pretty obvious and such a simplistic thing being discussed, just saying what I did/do for these things.
Fair enough! I guess you always have a choice whether to go Heath Robinson or cough up for the tool which has been designed for the job. It's no big deal. I've been milling aluminium with a router because I can't afford a mill! It depends where you draw the line. I have just developed an irrational love of counterbores since buying a set recently and want to spread the joy!!
Yes I found that. I bought my m12 from arc euro and a set of Ruko m3-m10 on eBay but only because I spotted a good deal, can be quite pricy otherwise.
Think I have the bolt problem sorted now...will update soon. Now on to the next problem...
I was playing with my ball...screws last night before bed ;) I've noticed that the Z-axis ballnut (RM1605-C7) seems a little notchy and not smooth. As if there could be some swarf or something inside? The ballscrews are covered in a light machine oil (I assume to prevent oxidisation). Do I needto strip down and clean everything before use? Do the ballnuts require greasing first?
On a similar note, is there any specific preparation I need to do to my linear rails/bearings before use? (I need to assemble the HIWIN ones).
On my HiWin, I followed the manual, I used light grease and worked it in slowly by running the carriage up and down by hand and giving a little grease each time, this is done on the rail of course ;)
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