I keep killing these damn bi-metal hole saws. They only last long enough to get one or two holes drilled for the bung.
I have here in front of me my MSC master catalog and they have plenty of different types of holesaws. Which ones last the longest? I dont really care about the cost as long as I can re-use them after 1 or 2 times, lol.
The Remgrit tungsten carbide cutting edge saws look promising and not bad at only $17 each....any feedback on these? Or the brazed carbide saws which are a bit more expensive at $60 each but boastes that they outlast high speed or bi-metal saws up to 100x.
Any help is appreciated, thanks.

 

i dont know how big you need it, but have you ever tried one of those step bits? i dont know what the real name is but they start out small and get bigger. i dont know if it would work but i figured i would throw out a suggestion

 

A uni-bit. Nope wont do ****. Just put it in the drill press and tried it with no luck.
Im shooting for either a 7/8" or 3/4" hole.

 

no hole saw will work just go get a big dril bit

 

for something that size i would just use an 1/8" bit. then go to a 1/2" bit. then the final size. it may take a little longer but your bits will last a lot longer

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93LSivic &raquo;</TD></TR><TR><TD CLASS="quote">A uni-bit. Nope wont do ****. Just put it in the drill press and tried it with no luck.
Im shooting for either a 7/8" or 3/4" hole.</TD></TR></TABLE>

wha??? i have used many different unit bits as well as hole saws for entended amounts of use. What are you drilling through? I have drilled holes is 1/2" plate for SS flange with a unitbit and no probs what so ever (and very fast to, using around 200rpm, lowest sitting my drill press goes to with some good cutting fluid). What speed are you drilling these at? I have reused my starrett hole saws from wholesale tool like 15 times on 8 gauge ss tubing, and it still works, it just cuts slower now. Sounds like you are turning it too fast and prolly eating away at the life of the saw.

 

i probably do atleast 10 bung hole installs on cars a week..on the car with the car up in the air. i usually use a small drill bit to make a pilot hole....and usually will just use the unibit till i get to the correct size. my unibit has lasted atleast 50 bungholes......make sure you use wd40 while your drilling. all of my unibits are dead now so i need to order some more...so i have just kept stepping it up with normal drill bits. takes a little longer......something isnt right if you can only get 1-2 uses out of your bits.

im looking for some higher quality drill bits myself, im going to talk to my machine shop about it tomarrow. if they have any worth while info i'll be sure to post it here.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Turbo-charged &raquo;</TD></TR><TR><TD CLASS="quote">my unibit has lasted atleast 50 bungholes...</TD></TR></TABLE>

Wow, that's a lot of bung holes drilled. Sorry, I couldn't help myself.

Anyways, for the hole saws, you're probably going too quickly, slow it down, lighter pressure, and lots of lube.

Use cutting oil, not WD-40, it's not thick enough and burns away quickly.

 

since we're on this topic, where do you guys get teh actuall bung? I would prefer a SS one.

 

Local hardware store hooks us up, we just get a case of SS 18M x 1.5 nuts. Then I buy all the 18mx1.5 drain plugs at the local auto parts store. When the wideband isn't in, plug it with the drain plugs instead of a dead O2.

 

i have a set from wholesale tool 3/8"-1" cobalt 135 degree bits (i think they were 30 bits), it costs about 150 bucks but they work like a dream. plus i have a drill doctor to and it helps.

 

This is kinda funny, not laughing funny .But I always use a hole saw .This last one has lasted more than 2 years with 2 teeth on it.And i cut at least one a day.But when it was new it cut like ****.until all the teeth broke off.Don't ask me why.But now it cuts like a S.O.B.

 

hmmm i always that i was the only one with that sort of magical holesaw. Some of mine do the same exact thing. its weird, once the teeth lose half there height it cuts better.

 

The way you use a hole saw will make more difference in its lifespan than what brand it is.

When drilling, you have to keep in mind that turning speed does NOT equal cutting speed. Turning speed equals heat...which dulls the blade quickly. So, if you turn too fast (especially on stainless), the teeth dull and then your cut speed is decreasing rapidly.

The trick is to turn SLOW!!! You want to turn slow enough that you can just about count the rpm's....even more so on larger diameter hole saws. On the 3/4" you are using, go with something like 1-2 revolutions per second. Further, USE COOLANT!!!! Oil works, machining coolant works, and even water will help. I really like water because it's cheap and you can use a spray bottle and just flood the part, keeping it cool as possible. You will find that keeping temps down will increase your cut speed.

 

Well nothing neg. out of me.I looked and couldn't find anything that I disagree
on. lol.That's exactly the way I would do it.A mill cuts real slow and no chatter.
I'm outa here. PEACE!