RPM for countersinking in mild steel

[goldstar31]

All that is going on is drilling with a drill of a different angle to the one which is currently the norm.
Lot of fuss and expense by not going back to basics. Tut, tut!

 

[jack620]

Rob, could you provide a link to some metric tables?

Rod,
is this what you are looking for?

http://www.bordo.com.au/pdf/Countersink_usage.pdf

 

[MuellerNick]

What do you mean by "proper"?

??? My dictionary says "right", "fitting", "suitable".
With HSS, you can go down with the surface speed. You don't lose that much, except time.

If the chips get yellow, reduce speed to get more tool life. Yellow is the upper limit for HSS (a rule of thumb).
Carbide tools should make blue chips.

Nick

 

[gus]

Gus, I love the boat!

Hi Rob,

When you drop by,Gus will take you out for a spin and beer.

They have a quote in Singapore among the fishermen. Boat fishermen live longer. My be true.Gus is going 70 in August. Hope to fish another 8----10 years more. Our engine building hobby too. Gus gets up and he has some parts to turn or do some housekeeping.

See you.

 

[Tin Falcon]

IIRC general rule of thumb use 1/2 drilling speed for reaming and countersinking.
I know late in the discussion and you found what works.
Tin

 

[rodw]

Guys, thanks for all your help. Remember though some of us are not machinists by trade and are figuring stuff out themselves so we don't really know what the basics are to go back to. I started making this part back in 2009 so I thought it was a pretty trivial thing to make but on this (big) batch, things went haywire. I suspect a lot of the problem was not being able to accurately centre the hole under the countersink on my entry level drill press and compound vice. Once I squared up the jig in my little mill and indicated it in with an edge finder (another first for me), most of the problems went away. Having a machine which needs belt changes for every speed change is not a good thing but I am working on a remedy for that! Hopefully, I will have my new lathe by the weekend and my existing machine is on eBay as we speak.

Jack, thanks for the link I'll save that one for reference.

When you drop by,Gus will take you out for a spin and beer.

They have a quote in Singapore among the fishermen. Boat fishermen live longer. My be true.Gus is going 70 in August. Hope to fish another 8----10 years more. Our engine building hobby too. Gus gets up and he has some parts to turn or do some housekeeping.

Gus I look forward to the beer! When you describe it that way, I can understand why you spend so much tie in your shop! I am sure now that you have isolated the cause of your wheezing, and applied the Makita remedy, you will outlive them all AND keep all your fingers!

 

[gus]

Guys, thanks for all your help. Remember though some of us are not machinists by trade and are figuring stuff out themselves so we don't really know what the basics are to go back to. I started making this part back in 2009 so I thought it was a pretty trivial thing to make but on this (big) batch, things went haywire. I suspect a lot of the problem was not being able to accurately centre the hole under the countersink on my entry level drill press and compound vice. Once I squared up the jig in my little mill and indicated it in with an edge finder (another first for me), most of the problems went away. Having a machine which needs belt changes for every speed change is not a good thing but I am working on a remedy for that! Hopefully, I will have my new lathe by the weekend and my existing machine is on eBay as we speak.

Jack, thanks for the link I'll save that one for reference.

Gus I look forward to the beer! When you describe it that way, I can understand why you spend so much tie in your shop! I am sure now that you have isolated the cause of your wheezing, and applied the Makita remedy, you will outlive them all AND keep all your fingers!

Hi Rod,
From day 1 in Trade School,the hacksaw was never my favourite tool.
Just imagine way back in 1955,the machineshop next door,had a contract to mill 100 spur gears tooth by tooth and manual hacksaw 100 gear blanks from 4" shaft. My young classmate was given the job of cutting gear blanks.Quite a character,it was his polytechnic holiday job and he needed the cash to pay for his daily bus fares and meals to attend class. Ask any engineering college internee to do same today,he will think you are mad.Till today my class mate is still good at manual hacksawing.

OK. At 9am will go balcony workshop to cut material for my deep sea rod holder.No more manual sawing equallllllllls to no procrastination.

When a '69 going 70' retiree gets busy turning,milling parts,time passed so fast.

Bye ,

Gus.:fan::fan: