Hole saw question

I actually come up with 60 rpm from here:

http://www.fairburyfastener.com/holesaw_speed_chart.htm

Also noted they suggest about 300-350 lb of force on that size hole saw... 😮 Never realized you were supposed to use that much force but I guess it makes sense.

I would try to use as much force and as low of rpm as you can and to stop frequently to allow the drill to cool. No easy solution unfortunately.

Thanks. Another thing I ll try is using no lubricant - as specified by the hole saw folks when cutting cast iron. Gonna take a while......

when using large hole saws with high speed drills I always find its best to pulse the drill if that makes any sense I always have used lube but saying that have never really drilled much cast iron so if they say use none thats what I would
The most important thing I find when drilling thru something thick is to clean the cut out constantly with compressed air because most hole saws arent self cleaning and seems to work a lot better when doing this

Paul

my tip: use special drilling flued, is a mix of 90 % water and 10 % special oil, wich if mixed convert in to a milky white supstance. constant poor it on easyest with a bottle and small hole in the lid and so cool it and its taking away the "sawdust" . pulsating drilling/sawing and so cleaning the saw/bit

To help clear the chips I sometimes drill a hole (1/4-3/8 ) or two at the outer edge clean threw to give the chips a place to go.

To help clear the chips I sometimes drill a hole (1/4-3/8 ) or two at the outer edge clean threw to give the chips a place to go.

[quote="TOGNOT"]I ask this because I thought others could use this info. I am drilling holes in my D2 bell housing for my starter installation. I used a jig and go the first two holes done. The third hole nearest the engine block appears to require a longer drill bit so my drill chuck will clear the block. SO.... I started on the big hole:

My 1\2 drill is a variable speed. I look online and see a 3.5 " or 3 3\4 " hole saw should be spun at a pretty low rpm ( less than 100 rpm) . My drill get hot trying to run it this slow.

What speed do you goes estimate is ok ? I have another 1/2 drill that runs at 500 rpm but that seems to fast.

Normally I wouldn't give it this much thought but I am going to be drilling on this a looong time....

Thanks for expert advice ![/quote]
Tognot, Where did you get a jig for the drilling or did you make one from Old Magnet's drawings? I'm wishing I would have at least drilled the bell housing and made a cover plate when I had my D2 apart a couple years ago.

I tried agian this morning and stopped after almost no progress. I ordered a carbide tipped hole saw that should be here soon.

In regards to the bottem inside hole ( next to the block) I bought a 3\8 drive ( stepped down ) bit. This will allow me to use my air drill and hopefully will clear the block.

I borrowed the jig from a friend who was kind enough to offer it.