|noel shelley||14/03/2022 17:51:33|
|1442 forum posts|
A friend called me to ask for help ! New to engineering, and had bought a lathe. He had invested in a GOOD set of drill bits - over £100, and found first he could not drill a 8mm hole in steel, then tried to drill 13mm in alli - NO GO ! I offered some suggestions but had not thought of this one !
Mentioned this to a local tool stockist today and he said look at the bits, and handed me an 10mm, I COULD NOT BELIEVE MY EYES ! It had been sharpened to a chisel edge, like a rotary percussion drill bit - then coated ! This was not a cheap bit, of 4 facet or split point design !!!!
Has anybody else had this problem ? It's a new one on me ! Noel.
|226 forum posts|
I have several sets of cheap Chinese bits that cut poorly until I properly sharpened them. I have a set of HSS bits that I bought decades ago, made in West Germany (remember that?!), that cut really well. Does the package mention material and Country of Origin?
|Chris Evans 6||14/03/2022 18:38:36|
2067 forum posts
I once bought a set of Guhring (spelling ?) drills 6mm to 10mm by 0.1mm From the start I had to grind nearly all of the to get them to cut.
|Tony Pratt 1||14/03/2022 19:24:01|
|2023 forum posts|
Even the 'good' brands are having to go cheap on their process to compete so you will get more & more crap hitting the consumers, and yes this problem filters though to industry as well.
23042 forum posts
The good brands have so many different spec drills these days a lot depends on which one you go out and buy as to whether you get their DIY or Quality offerings.
I think Dormer have over 50 types of HSS drill bit and that is just familiar twist drill style not the odd ones like spot, step, csk, etc. And the same again in carbide before you even get onto the indexable ones.
|Speedy Builder5||14/03/2022 19:56:21|
|2649 forum posts|
Noel, your friend need a set of these.
|noel shelley||14/03/2022 20:40:26|
|1442 forum posts|
HeY Speedy, Do warco or chester supply a drilling machine to run these drills ? Noel
8883 forum posts
Strange - a £100 set of 'good' drills are all faulty? Might be counterfeit. But then a tool-seller independently produces another example, which implies it's a common problem. A 'good' maker is producing lots of dud drills? Have they gone south, or could the drills be a specialist type?
A picture would be good - the angle, grind-type, flute arrangement etc might reveal all. The good, the bad and the ugly!
|David-Clark 1||14/03/2022 21:22:24|
222 forum posts
Guhringused to be good drills. They sound like the type of point they used.
they did them in various angles as well as 118 degrees.
we used some of them for sheet metal and other angles for hardened aircraft steels.
They never failed to drill.
Have you checked they are right-hand twist? You can get left-hand drills for drilling holes with Britann capstan for spread of production.
I have some in the shed but not sure how long before I get to them.
|BASS 666||14/03/2022 21:57:46|
49 forum posts
hi guys it was me who rang Noel to tell him i was having a lot of bother using the drill set i bought ... so i done a bit of homework and i don't know what if anything is wrong so help me understand i have the correct drill set ... here is the set i ordered ...... https://www.rdgtools.co.uk/acatalog/Presto-09501M25---M25-COBALT-DRILL-SET-1MM---13MM-IN-0.5MM-28299.html#SID=207
i bought them from RDG but the set that came are these .. i found them on Ebay, are they the same and if so look at the price difference ....
why the big price difference and why the different case they are in ? are they the same bits ? thanks guys ...
8883 forum posts
Ah ha! The RDG set are 'Heavy Duty' drills, which are for punching through hard materials. The cutting edge is like a masonry drill, with a shallow angle to reduce wear, and the flutes are extra thick which increases friction as holes deepen. Good for difficult materials like Stainless and hardened steel. They don't cut as well on Mild Steel, Aluminium and Brass as ordinary drills, like the Presto jobber set on ebay.
You'd think buying an expensive heavy duty drill from a reputable maker would guarantee wonderful drilling, but the drills aren't ideal for the alloys we normally machine. Not really a waste of money though because sooner or later it will be necessary to drill an awkward material - then they'll do the job.
I buy mid-price HSS drills from ArcEuro, Tracy Tools and others and they generally work well on usual metals. I avoid cheap DIY store and internet drills because quite often they're for woodwork or just too cheap. I rarely buy 'good' brand-name drills because although they stay sharp longer, I don't do enough drilling to justify the cash. Owning tools that will last longer than I do doesn't seem sensible when the money can be better spent on other tools. For example, I bought two sets of mid-range drills, and keep one specially for Brass which likes sharp. Once a drill has been used on steel, it's spoiled for Brass, but drills eventually too blunt for Brass still cut steel OK.
5170 forum posts
That picture is a cracker...
I got a cheap cobalt set and they were very variable, a few bits were great and a lot were bad, a couple were actually wobbly and one was like glass it was so hard
I think what I got was a set from the rejects bin in China
The good cobalt ones really are good, better than hss for tough jobs
edit: when the big 15quid boxes of hss showed up a few months ago in Lidl I grabbed a couple, they've been very reliable
Edited By Ady1 on 14/03/2022 23:19:33
|pgk pgk||14/03/2022 23:29:30|
|2603 forum posts|
My specialist area of engineering expertise is making stupid mistakes. Most of my drill bits are jobber quality cobalt from UKDrills and have worked very well. However, when asked by a friend to pop some holes through unknown steel plate I failed totally despite reducing drill speed and some serious weight on the mill handle and even being desperate enough to try assorted brand new drill bits, and even a tungsten masonry drill.
|Howard Lewis||15/03/2022 09:34:26|
|6306 forum posts|
You are not alone pgk pgk.
As an Apprentice I was told that the man who never made a mistake never made anything.
And promptly went and ran a small Theil universal milling machine in reverse and wondered why it did not cut!
In my experience, any drill performs better once it has been Four Facet ground.
|noel shelley||15/03/2022 10:20:14|
|1442 forum posts|
One day I will hold open house and you can all come and play with the brierley drill grinder, you can have 2 facet, 4 facet, or no facet at all ! There's a good set of cams so the choice will be yours. Noel.
|Simon Williams 3||15/03/2022 10:50:25|
|662 forum posts|
'ang on chaps, we've got lost in the brambles somehow.
The OP's (and his friend's) original query was "why do my (expensive) (Presto cobalt) drills not cut at all?"
Notwithstanding the niceties of whether these sets of drills are overpriced, on the face of it they ought to at least cut holes when offered up to a bit of steel or aluminium. But they don't, or so is reported.
So can we see a picture of the actual drills that don't cut please. In focus and showing the shape of the tip side on please. 'Cos they're either being run backwards or they're ground wrongly. The steel could have work hardened, but the aluminium isn't.
The drill with a carbide tip ground in a wedge is a perfectly usable thing, I've got a set of them and they are for drilling hard steels. You essentially melt your way through, so you need a fair amount of power to drive them. They're not for the faint hearted! This doesn't, however, inform the OP as to what is the problem in his particular instance.
I'm looking forward to a picture.
1782 forum posts
I'm with Simon here; I might be misunderstanding something due to insufficient coffee, but are Noel's first two paragraphs directly related to each other.
|3563 forum posts|
If you have a problem with a purchase from RGD, why not contact Richard and ask the questions you have?
|old mart||15/03/2022 14:20:03|
|3892 forum posts|
Genuine Guhring drills are second to none and I suspect there are counterfeit copies around.
|alan ord 2||15/03/2022 14:51:33|
127 forum posts
Talking of counterfeit copies, I recently bought a bunch of Brazil manufactured Dormer drills off e bay at a very reasonable price. During my search of e bay I came across a lot of cheap Dormer drills and started me wondering if they are copies/fakes. Anybody got any thoughts on this or am I just paranoid.
Edited By alan ord 2 on 15/03/2022 14:52:23
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