Spotting Drill or Centre drill.

I was watching a Clickspring video on YouTube the other day and noticed that like me he used a spotting drill to start off a hole on the lathe and wondered how many others do this. Or do you use a centre drill instead?

Edited By Vic on 09/02/2018 12:46:24

Spotting drill for me all the time in lathe and mill unless I particularly need a ctr hole

Spotting drill. I'd like more sizes than I have too.

I switched to using a spotting drill a year or two back, and only now use centre drill when I need a 60 degree centre for between centres turning.

I wish I could find a low cost source however. Spotting drills seem very expensive compared to centre drills.

Five bob each way here. I often use a larger size centre drill but use only the tip of it to put a small divot in the job, as one would do with a spotting drill. This works real well for tiny size drills where if you use the appropriate tiny sized centre drill in wobbly ancient machinery (or is it the wobbly ancient operator?) it is soooo easy to break the tiny tip right off it.

Yes, they do seem a bit expensive don’t they.

I must've led a sheltered life in engineering - I'd never heard of a spot drill before I read this thread.

They're eye-wateringly expensive.

Although I've occasionally broken centre drill pilots, it's always been when I was impatient to drill the 60 degree cone in something difficult, not when I was spotting to guide a standard twist drill.

I think I'll stick with centre drills.

On the milling machine I rarely use spotting drills and never use centre drills. A 4-facet drill starts accurately enough without needing either. When I do need extra precision, or the surface isn't flat, I use a carbide spot drill to start.

On the main lathe I use centre drills; they're way cheaper than carbide spot drills. On the Britan I use LH centre drills.

Andrew

To Mike and Vic,

Look up a place called "Drills UK",They sell spotting drills,double ended,and not at all dear. I bought some MT drills from them a while back and am quite pleased with them. Along the way,I saw those spotting drills in many different sizes.I bought a pack of 10 5mm stub drills for £4 ,95.,are these what you are looking for?

I just use 1/8 and 3/16 spotting drills, I like the Americam made Keo brand as they have the smallest "flat" between the webs that I have found. Don't think £2.42 inc vat from MSC is too bad though they are not stocking them anymore so just some left in the clearance except the 1/8" ones as I just bought their last 4 in stock

A lot depends on what I'm drilling like Andrew I will use a split point Dormer straight onto the metal in some cases particularly if I have got the stub length needed and I have most of the common sizes in those.

Spotting drill .

Usually I'm repairing a shaft by drilling and tapping. Go in deep enough so when I thread it doesn't pull the surface up.

1 less operation!

Cheers Michael.

I’m not looking for any at the moment as I have 6, 8 & 10mm spotting drills. They are not the same as stub drills.

I pretty much use centre drills for everything, but for some very soft materials I don't even bother as there's pretty much no resistance to the point when it goes in, provided it's a split point drill. 

I honestly was never shown spotting drills when training and only discovered them through youtube and watching others on the forum, so i'll have to check them out one day.

Michael W

Edited By Michael-w on 09/02/2018 15:46:50

Spotting drills

Tony

For the folks using spotting drills are these 90 degree or 120 degree or another angle? I assume you follow up with a 118 degree or as near as regular twist drill.

Thanks,

Steve

I just use the 90deg ones as they can give the hole a chamfer at the same time and as Michael says if tapping that little chamfer stops the area around the hole being raised up particularly if tapping softer metals. Regular angled drill follows OK.

Sorry about that Vic,my mistake. I still have a lot to learn. I will look into that,I dont think I ever came across spotting drills but I did hear of stub drills,and I thought they were one and the same. I live and learn !

90 degree spotting drill for me too!

I mostly use a 3mm one, even for tiny holes, and follow up with a normal 118 degree drill.

Tom

All mine (which are in small sizes up to 3mm, came with those rotary tool accessory sets that contain lots of useful consumables and a few weird tips

Neil

Nah, still sticking to centre drills.

Those folk don't seem to be offering spotting drills unless they're the same as 'spot weld' drills - not double-ended either. Cromwell's spot drills seem to be around a tenner each, and they're not double-ended either.

Centre drill don't have cylindrical land and cut on the side as well as the point, so any eccentricity gets taken out. I've sometimes succesfully used the pilot as a tiny slot drill.

I can't see any substantial advantage in the spotting drill that's worth its price differential.