Pillar drill belt pulley speeds

[dan.taylor.1]

Hi folks,

another thread about this mystery "Progress" pillar drill of mine, just worked out (or at least as best i can trying to remember physics and mechanics equations!) the speed of the driven pulley by using the equation Driven RPM = (Drive RPM x Drive Diameter) / Driven Diameter.

Can someone who knows tell me if ive worked this out right: -



CHeers, Dan

 

[AndyStobbs]

They all are correct

 

[rtbcomp]

Yup - all correct

 

[dan.taylor.1]

Ah glad my minds not melted then... Shame it's not a bit slower. Any idea what speed hole saws like?

Dan

 

[brightspark]

Ah glad my minds not melted then... Shame it's not a bit slower. Any idea what speed hole saws like?

Dan

as slow as possible and use cutting compund

 

[julianthegypsy]

Ah glad my minds not melted then... Shame it's not a bit slower. Any idea what speed hole saws like?

Dan

Much slower! I'd have mine on its slowest speed- that's 80 rpm! You can easily calculate it though. I take cutting speed for mild as 32 feet/minute because I'm ancient, then convert it to metric because I've forgotten how to do sums in proper money, figure out the circumference and do maths things or something to give me drill speed

 

[dan.taylor.1]

I'll leave them for the mag drill then....!

Dan

 

[Paul99]

Ah glad my minds not melted then... Shame it's not a bit slower. Any idea what speed hole saws like?

Dan

Here's a copy of the leaflet that come with starret hole saws:

I've only used 25mm and 30mm ones and personally think they cut better and certainly a lot cooler at much much slower speed (80 - 130ish rpm) but using a lot of oil and plenty of downward pressure to make sure it's cutting rather than just rubbing. I also find that they cut even better again if you drill a relief hole through the work so that it allows the swarf and cutting oil to drain out of the channel the teeth saw like this:

 

[julianthegypsy]

Interesting. Much faster than I would have expected.

 

[brightspark]

Interesting. Much faster than I would have expected.

quite a lot of hole cutters are used in hand pistol drills on the slower speed but are still quite fast

 

[julianthegypsy]

I suppose having multiple saw teeth rather than the two cutting faces of a drill ups the speed, rather like a four flute mill compared to a two flute?

 

[Windy Miller]

I use engine oil on the hole saws - would proper stuff be noticeably better? I have a Cheapo drill press that's too fast too

 

[naughtyboy]

you could fit pulley set in middle of other two if youve got space.
did it with mates drill press.
going to be doing it with one my boy pulled out of skip as its designed for woodworking.

 

[dan.taylor.1]

Yeah there is probably room **********, would have to be small though, and the belt atm is only 49" so the new ones would be tiny!

Dan

 

[brightspark]

I use engine oil on the hole saws - would proper stuff be noticeably better? I have a Cheapo drill press that's too fast too

oil is a good lubricator but cutting compound is far more superior

 

[Windy Miller]

oil is a good lubricator but cutting compound is far more superior

Ill have to get some. I remember Rocol from may apprenticeship many years ago. Is that still about or is there something else that is used widely now? I think I probably need some!

 

[julieanncharters]

Ill have to get some. I remember Rocol from may apprenticeship many years ago. Is that still about or is there something else that is used widely now? I think I probably need some!

yep rocol still available

 

[rtbcomp]

I use Rocal cutting fluid, it is still available, but expensive. Try CPC or Cromwell

 

[Windy Miller]

Thanks Guys - I'll get busy googling!