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Member postings for Robin Graham

Here is a list of all the postings Robin Graham has made in our forums. Click on a thread name to jump to the thread.

<< First < Prev 50 51 52 53 54 55
Thread: Drilling problem - the sequel.
22/10/2009 20:41:27
Hi Chris, thanks for your welcome to QTAS. 'Tis too true.  I had a similar experience with taps/dies - having blown most of my start-up budget on the lathe, I went for a cheap (about 30 quid) set of dies and taper taps.  I then needed a bottoming tap for some reason and bought one-off from a 'proper' engineering supplies merchant (about a fiver for one tap). And then worried that I'd cut the core too big 'cause it slid through so easily...
 I'm attracted by your idea of modifying the cheapo drills, though I confess I don't quite understand your instructions, but shall think on't.
Regards, Robin.

22/10/2009 19:51:20
Thanks Rob - that's reassuring. I shall try clamping the quill somewhat as you suggest.  I was going at about 800 rpm - the lowest speed the machine offers is 500rpm.  Would that  still be fast by your standards?
Regards, Robin
22/10/2009 19:00:31
Hello. I picked up a set of Dormer drills (to replace the cheapo Screwfix set I had been using)  and a Rohm chuck and arbour (to replace those supplied with my Axminster drill press) at the Midlands ME exhibition last weekend.  Good Lord, what a difference! Apart from the fact that the drills cut so much faster and with far less effort than the old ones, I'm now getting parallel bores.  However...whilst drilling aluminium and steel is fine, if I try a smallish (4mm) hole in brass, after getting in about 1mm the bit decides it can do without my help and pulls in to the work for another 2-3mm on its own (noisily and at alarming speed!). Things then go normally for perhaps 0.5mm, then the same happens again and so on. At larger diameters (>6mm) the chuck actually pulls out of the spindle taper. Any ideas as to cause / remedy?
Regards, Robin.
Thread: Drilling problem
14/10/2009 21:48:37
Thanks again for all your advice - though some of it was way over my head.(4-facet sharpening. Eh? So much interesting stuff to learn!) I am now convinced that a decent set of drill bits is a necessary investment, and shall present my Case for Support to the to the purse-holder for urgent consideration.
Regards,Robin
10/10/2009 19:08:54
Many thanks all for your useful comments.  I had in fact set the table as square as I could left-to-right but there is a residual error of about 0.1mm in 100mm (ie about 0.06 degrees) fore-and-aft which I imagine can be corrected only by shimming somehow.
I tried the test for play which Jeff suggested and found that there is indeed significant 'wobble' - I could 'scribe a line' nearly 1mm long with the tip of the 8mm drill bit by grasping the chuck and pulling on it.  I then tried replacing the chuck and arbour (hope that's the right word - the thingy with B16/MT2 tapers on it) supplied with the press with those which  came with the lathe.  The play was reduced by an order of magnitude which suggests that the problem is with the chuck and/or arbour.
The drills I am using are from a cheap (about 7 quid) set of 19 which I bought years ago from Screwfix, so that might not be helping either.  My general experience of tooling so far is that it's very much 'you gets what you pay for'. Which prompts my next question... is it worth shelling out say 50 pounds for a set of Dormers?  
Thanks again for all your suggestions and general advice on making holes in metal,
Regards, Robin. 
09/10/2009 22:21:45
Thanks Chris, you are not being dense at all! I didn't drill in the lathe (which I knew should work) partly because I was trying out a different method just to see what would happen  and partly beacause I wanted to see what the (cheap) new drill press could do. I have no  background in mechanical engineering, so I'm still experimenting.
Your explanation  of the reason for the 'conical bore' makes good sense to me.
Thanks  again, Robin. 
09/10/2009 20:22:38
Hi, I have recently acquired a drill press (one of the smaller Axminster bench-mounted jobs) and today used it to drill  8mm through the axis of  a 1.5 inch long piece of 1.25 inch diameter round steel bar.  The procedure I adopted was to turn the bar to diameter in the lathe, centre drill whilst still in the chuck then transfer to the drill press for drilling through. I clamped the bar in a vice, aligned the centre-drilled hole in the workpiece with the drill bit as best I could by eye, tightened the vice to the table and chewed my way through.
The problem is that the resulting bore, whilst spot-on 8mm (as near as I can measure) at the 'exit hole', is around 8.5mm at the 'entry hole'.  Can anyone explain what is happening here?
Thanks in advance, 
Regards, Robin.   
 
Thread: Small Milling Machine
30/09/2009 21:04:34
Many thanks Phil and Peter for your responses to my post.  I think I'm veering towards the WM-14 - despite Peter's reassuring remarks, the idea of having to bash out bearings to change the gears scares me stiff. I'm very new to this - I've had a lathe for only four months, and have no background in engineering.  Perhaps I'll get down to the midland ME exhibition next month and see the machines 'in the flesh'.
Concerning the belt drive modification to the generic X2 mills suggested by Stewart Hart  (which I had been considering as a possibility for the Warco mini-mill) I guess that the kit he refers to is that offered by Stirling Steele. They have a video on their website showing how to use their kit to replace the gear train, and it seems far less daunting than the process Peter describes for replacing the gears - which makes me wonder if the differences between the Warco machine and the Sieg X2 are more than superficial.
Thanks again for your replies, and also to David Howorth for starting what (for me at least) is a very interesting thread.
Regards, Robin
 
29/09/2009 17:32:39
I am in a somewhat similar position to the OP and have read the above with interest - I had been considering the Warco mini-mill as well, but I'm a bit put off by hearing that it suffers from the notorious plastic - gear problem.  As a complete tyro I suppose I'm bound to shear the gears probably sooner rather than later and the process Peter describes for replacing them sounds rather daunting.  Also I have read that the gears are pretty noisy - not good for me as my 'workshop' is in the house.
 Has anyone any experience of Warco's WM-14 mill? It is a bit more expensive, but does come with 'an individual accuracy report' which might indicate that Warco have more confidence in the build quality.
Regards, Robin
<< First < Prev 50 51 52 53 54 55
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