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Drill running off course

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Ron Laden17/09/2019 15:51:37
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Well using centre drills for starting drilled holes may be considered incorrect but it is what I do most of the time unless of course the hole doesnt need much accuracy. I cant see a problem with it, it works well enough, for me anyway.

Edited By Ron Laden on 17/09/2019 15:52:16

JasonB17/09/2019 15:52:09
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You do need to read the drill lengths, those two spotting drills there would be about 10mm long if you went by the picture in the catalogue.

Yes long series Ctr drills good for things like valve guide sin the end of valve chests, pairs of bearing housings I have them upto 4" long though easily damaged. Will possibly add a LS spotting drill to an order some time.

ChrisB17/09/2019 16:56:41
400 forum posts
162 photos

You can use straight shank stub drills (used mostly for sheet metal) to start the hole. They will not wander off. You cannot drill very deep with them as the flutes are short and they have no side margin, good for about 3x the dia. but that's enough to get you started.

The drill on the right.

20170619_154724.jpg

Andrew Johnston17/09/2019 17:21:58
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I use centre drills for making centres, and for starting drills, on the lathe. embarrassed

But I never use them on the vertical mill. For general work 4-facet drills start fine, on a flat surface, without the need for spotting or centre pops. If I need better location accuracy, less than 2 thou, I'll spot drill first. The trouble with centre drills is that it's only too easy to break the tip on a vertical mill. And they're not much use for small drills as the tip is bigger than the drill.

Centre pops are only used when I'm drilling by hand (mostly sheet metal) or for rough 'n' ready holes using the drill press.

I expect that in industry spot drills are not held in drill chucks, but collet chucks or similar where the length can be accomodated.

Andrew

Vic17/09/2019 17:39:34
2256 forum posts
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Jason, where are you buying your dumpy little spotting drills from? Mine are much longer. Let me know, save me cutting them down.

bf74af43-3cda-4413-9d78-e4d67e59e0ea.jpeg

Edited By Vic on 17/09/2019 17:40:25

old mart17/09/2019 17:49:24
592 forum posts
54 photos

I use spotting drills on the mill and centre drills on the lathe, where the 60 degree matches live and dead centres. I also have some centre drills with a 90 rather than 60 degree angle, I'm not sure what they are intended for, but I use them for subsequent drilling.

It pays to use a new drill bit if the hole is critical, a good make if possible.

JasonB17/09/2019 18:34:18
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Vic the Keo ones in the photo came from MSC but they don't do so many of that make now probably because Keo are American so mostly imperial diameters, have a look on page 23 the Hertel and Interstate are reasonably short.

The 3mm Carbide I recently got is a little longer at 50mm but the length doe snot change for the next few sizes up from APT's own brand. Cutwel do similar lengths though not used them for spot drills.

larry phelan 118/09/2019 10:51:13
508 forum posts
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For what it*s worth;

Many moons ago, long before I had a lathe, I needed some drill bushes for a jig.

The finished size was 5mm ID X12MM OD X20mm long.

The price I was given was WAY over the top, so I had a go at making them myself using silver steel cut to length with a hacksaw.

Th blanks were mounted in the drill chuck and a centre drill mounted in a vice on the table, next best thing to a lathe.

First piece was marked and centre punched as near centre as I could get it, then lined up with the vise held centre drill, centre drilled, then drilled out 5mm with drill bit held in vise. Repeated this for the remainder, and to my surprise there was no runout that I could see. Having a few spares, I decided to see how big I could go before the drill broke through the side wall. I stopped at 10mm, leaving a wall of 1mm, so it can be done.

Just try keeping the drill fixed and the job revolving. Worth a try.

Mick B118/09/2019 11:34:58
1189 forum posts
66 photos
Posted by JasonB on 17/09/2019 14:14:09:

I've been using spotting drills for the last 5-6 years and only use my ctr drills for where ctr support is needed of conical holes for pipe fittings. I get away with just two sizes - 1/8" and 3/16" though have just recently bought a 3mm one for the CNC as I only have metric collets for that.

...

Well, I've looked around the net for spotting drills and not found a 5mm x 90 deg. example for less than a tenner. Even at 5mm diameter, the 90 deg pre-countersink possibilities are almost nonexistent, as even an M3 csk head is larger. I don't think they hold enough advantage over centre drills for me unless I can get bigger ones cheaper. Maybe that's why ME stockists like Chronos don't seem to hold them.

But thanks for posting your explanations - it might be different if I was starting from scratch.

Stuart Bridger18/09/2019 11:45:49
346 forum posts
17 photos

I bought a carbide spotting drill 5mm x 50mm from MSC a number of years ago. It gets used in the lathe and mill. It certainly wasn't cheap, but a worthwhile investment.

Howard Lewis18/09/2019 15:10:22
2341 forum posts
2 photos

Now there's a thought!

Grind centre drills with broken ends, so that they become four facet spotting drills!

Must try that!

Howard

Vic18/09/2019 15:50:24
2256 forum posts
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Posted by Mick B1 on 18/09/2019 11:34:58:

Well, I've looked around the net for spotting drills and not found a 5mm x 90 deg. example for less than a tenner. Even at 5mm diameter, the 90 deg pre-countersink possibilities are almost nonexistent, as even an M3 csk head is larger. I don't think they hold enough advantage over centre drills for me unless I can get bigger ones cheaper. Maybe that's why ME stockists like Chronos don't seem to hold them.

But thanks for posting your explanations - it might be different if I was starting from scratch.

I’ve got four or five at the moment and they were all under a tenner including a solid carbide 8mm one. I’ve just done a search and there’s a 5mm one on eBay for £4.60 inc postage. It’s a UK seller as well.

JasonB18/09/2019 15:59:02
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Posted by Mick B1 on 18/09/2019 11:34:58:

Well, I've looked around the net for spotting drills and not found a 5mm x 90 deg. example for less than a tenner.

Should have tried the links I posted further up the page carbide 5mm and 6mm 90deg for £8.40 inc vat. or HSS 8mm for £8.76

Or better still the MSC flyer often has their items discounted, could get HSS 10mm for under a tenner from them.

Mick B120/09/2019 13:49:48
1189 forum posts
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Posted by JasonB on 18/09/2019 15:59:02:
Posted by Mick B1 on 18/09/2019 11:34:58:

Well, I've looked around the net for spotting drills and not found a 5mm x 90 deg. example for less than a tenner.

Should have tried the links I posted further up the page carbide 5mm and 6mm 90deg for £8.40 inc vat. or HSS 8mm for £8.76

Or better still the MSC flyer often has their items discounted, could get HSS 10mm for under a tenner from them.

Thank you, I've got the pages saved. I'll give them a go if I break or blunt one of my current centre drill pilots.

MC Black 201/10/2019 22:32:33
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Posted by Vic on 18/09/2019 15:50:24:
I’ve got four or five at the moment and they were all under a tenner including a solid carbide 8mm one. I’ve just done a search and there’s a 5mm one on eBay for £4.60 inc postage. It’s a UK seller as well.

I've searched ebay and can't find anything like that.

I should be most grateful if you would kindly identify the seller, please

MC Black

Vic01/10/2019 23:30:43
2256 forum posts
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It‘s still on eBay for £4.60 for a 5mm.

**LINK**

The 10mm is only £6.70.

Free postage and says it’s located in Cheadle.

Ian Johnson 102/10/2019 01:16:50
138 forum posts
33 photos

I've been buying my spotting drills and milling cutters direct from Rennie Tools in Stockport for the past couple of years. Very good service, good quality and a simple secure web site, sign up and get regular updates and special offers too. Any problems and Johny will sort it out quick. Go direct and avoid ebay and amazon it's cheaper.

**LINK**

Typical disclaimer I've got no connection with the company I'm just a happy regular customer

Ian

Bill Phinn02/10/2019 01:41:39
208 forum posts
41 photos

I've bought items from both of the immediately above companies. I was unfortunate to get a duff product from the first company on my first order but the customer service in dealing with the problem was very good. I've bought small diameter milling cutters from Rennie Tool and they were certainly good enough for my needs.

paul ellis 502/10/2019 06:03:37
5 forum posts
2 photos

Hello all.

Just a thought, I would recommend grinding a negative relief on the cutting edges of the drill. This will make the drill cut bronze nicely. A standard twist drill straight out of the packet will tend to grab at the bronze and pull itself into the job, in any which direction it chooses. Also point thinning the chisel edge on the point will tend to make the drill keep to centre. Drill grinding is a simple thing to do.

Michael Gilligan02/10/2019 07:30:18
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14023 forum posts
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Posted by Ian Johnson 1 on 02/10/2019 01:16:50:

I've been buying my spotting drills and milling cutters direct from Rennie Tools in Stockport ...

.

Thanks for the link, Ian yes

MichaelG.

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