F pollard leicester corona drill which motor???

[thezetecman]

Hi

A few years ago I bought a Pollard made in Leicester corona high speed drill at an auction. It is a small bench drill very heavily built. probably weights 60 kg

The trouble is it has a 2850rpm motor fitted which means the minimum chuck speed is about 11400 rpm and the maximum speed is near to 15000.

Does this sound right?

I do not know what, other than PCB's what you would drill at those speeds.

I am thinking of changing the gearing to bring is down to about 4000 and 5000 rpm and add an electrical speed control giving a speed range of 2000 to 5000

Which I could use for drilling holes below 1mm in metal probably.

Has any one know what these were used for originally? or know anything about this drill I have searched the www and found nothing.

Thanks in advance for your comments?

 

[Bogstandard]

I have never heard of this make, but have seen and used a lot of PCB drills, which this is almost certainly is. Never one that heavy though

I for one, wouldn't touch the speed range. At the sort of range you are talking about is perfect for any small drills below 1mm. Around 90+K rpm is ideal for 0.01mm drills. The faster you can go the more rigid and less susceptible the drill is to breakage.

If you are just after a pedestal drill, I will buy you a brand new one and do a straight swap. (if you are UK based of couse)

John

 

[thezetecman]

Interesting,

I did not realize you could drill steel at that speed.

I got it running this evening (belt arrived in the post)

It drilled some very nice 0.33 mm holes in some mild steel.

I assumed 10K was too fast.

I have a pillar drill which is a bit slow for the small holes I want to drill.

Would that speed be ok on a brass or aluminium? should I sharpen the drill bit as I would for larger holes?

just needs some new wire and a paint, and ready for work

I would like to know the history though.

Regards
P

 

[Bogstandard]

P,

What you have there is a treasure. It will drill very small holes in almost anything. But do use a lubricant if you can, and 'peck' the holes thru.

In fact, if anything, it is a little on the slow side.

I would buy yourself some reground tungsten PCB drills and just see what it will cut. I think you will be amazed. By taking it steady, you should be able to drill thru a hand file, if ever you need to do that of course.

I think you would have trouble grinding very small drills.

Sorry I can't help on the history side.

John

 

[thezetecman]

Did some quick calculations

And a 0.33mm drill running at 10000 rpm is only cutting 10.37m/m on the outside edge.

So I see what you mean by slow if anything.

thanks for your comments

P

 

[tmuir]

I decided I needed to make myself a tap holder for my 1/8 inch BSW tap as I've got a stack of little domed nuts to tap 1/8 BSW.

I turned it up in the lathe and then moved to my drill press to drill then tap the 3mm thread for the locking grub screw.
Once I had it set up I realised I was using my shop made finger plate to hold the embryo tap holder and was using my previously made tap holder to hold the 3mm tap.

Life is getting easier in the workshop now I've got a few shop made tools in it.

Checking the fit out before blackening it.

My two shop made tap holders.
One is for 3mm taps and the other 1/8 inch.