Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Chris Smolinski
 
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Default 1 3/4 inch step drill bit ?

I need to drill a 1 3/4 inch hole in ABS plastic. I presently have great
luck doing this with smaller holes, up to an inch or so, using a step
drill bit. I've searched around the web, and the largest dia step drill
bit I can find is 1 3/8 inch - does anyone know of one that goes up to 1
3/4 inch?

--
---
Chris Smolinski
Black Cat Systems
http://www.blackcatsystems.com
  #2   Report Post  
Joe AutoDrill
 
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Default

Can you use a high-end hole saw type bit instead of a step drill? If so,
try Hougen.

If not, there are folks who will make you (read $$$) special tooling.

Hougen has a center point which is spring loaded and can be reversed to
guarantee plug ejection on flat or large tube holes. We have had tremendous
success with their product on metals and hard plastics. Haven't yet tried
them on wood...

Regards,
Joe Agro, Jr.
(800) 871-5022
http://www.autodrill.com
http://www.multi-drill.com

V8013


"Chris Smolinski" wrote in message
...
I need to drill a 1 3/4 inch hole in ABS plastic. I presently have great
luck doing this with smaller holes, up to an inch or so, using a step
drill bit. I've searched around the web, and the largest dia step drill
bit I can find is 1 3/8 inch - does anyone know of one that goes up to 1
3/4 inch?I need to drill a 1 3/4 inch hole in ABS plastic. I presently
have great
luck doing this with smaller holes, up to an inch or so, using a step
drill bit. I've searched around the web, and the largest dia step drill
bit I can find is 1 3/8 inch - does anyone know of one that goes up to 1
3/4 inch?

--
---
Chris Smolinski
Black Cat Systems
http://www.blackcatsystems.com



  #3   Report Post  
Larry Green
 
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I need to drill a 1 3/4 inch hole in ABS plastic. I presently have great
luck doing this with smaller holes, up to an inch or so, using a step
drill bit. I've searched around the web, and the largest dia step drill
bit I can find is 1 3/8 inch - does anyone know of one that goes up to 1
3/4 inch?



I have had good luck so far cutting plastics with 'wood' spade bits. I
recently needed a few 1.5" holes in some 3/4" thick nylon/polyethylene
blocks and only have a tiny Unimat DB200 lathe/mill. I had to go up in
steps as the Uni just didn't have the 'balls' to cut the 1.5" hole right
off. I was concerned about the bits 'wandering' as the point was not
cutting but with a rigid set up (using the Uni as a lathe) the holes
came out true and with an almost glass like finish. The size was bang on
to within a thou too!

I am fairly sure spade bits are available at 1.75" and they might be
worth a try (at least they don't cost much to experiment with).


--
Larry Green
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machineman
 
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Larry Green wrote:


I need to drill a 1 3/4 inch hole in ABS plastic. I presently have
great luck doing this with smaller holes, up to an inch or so, using a
step drill bit. I've searched around the web, and the largest dia step
drill bit I can find is 1 3/8 inch - does anyone know of one that goes
up to 1 3/4 inch?



I have had good luck so far cutting plastics with 'wood' spade bits. I
recently needed a few 1.5" holes in some 3/4" thick nylon/polyethylene
blocks and only have a tiny Unimat DB200 lathe/mill. I had to go up in
steps as the Uni just didn't have the 'balls' to cut the 1.5" hole right
off. I was concerned about the bits 'wandering' as the point was not
cutting but with a rigid set up (using the Uni as a lathe) the holes
came out true and with an almost glass like finish. The size was bang on
to within a thou too!

I am fairly sure spade bits are available at 1.75" and they might be
worth a try (at least they don't cost much to experiment with).


A forstner or sawtooth style bit would give you a better finish and
size, I find they work very well in polyethylene and nylon.

Lee valley have them in 1-3/4 for $15.40cnd

http://www.leevalley.com/wood/page.a...at=1,180,42240
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Tom Miller
 
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Try a holesaw. They are effective and relatively cheap.

Tom
"Chris Smolinski" wrote in message
...
I need to drill a 1 3/4 inch hole in ABS plastic. I presently have great
luck doing this with smaller holes, up to an inch or so, using a step
drill bit. I've searched around the web, and the largest dia step drill
bit I can find is 1 3/8 inch - does anyone know of one that goes up to 1
3/4 inch?

--
---
Chris Smolinski
Black Cat Systems
http://www.blackcatsystems.com





  #6   Report Post  
Chris Smolinski
 
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In article ,
"Tom Miller" wrote:

Try a holesaw. They are effective and relatively cheap.


I've tried one, and had terrible results, with a very rough edge and
melting of the plastic. Perhaps it was the particular one I used, or the
speed of the drill?

--
---
Chris Smolinski
Black Cat Systems
http://www.blackcatsystems.com
  #7   Report Post  
Chris Smolinski
 
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In article ,
Larry Green wrote:

I need to drill a 1 3/4 inch hole in ABS plastic. I presently have great
luck doing this with smaller holes, up to an inch or so, using a step
drill bit. I've searched around the web, and the largest dia step drill
bit I can find is 1 3/8 inch - does anyone know of one that goes up to 1
3/4 inch?



I have had good luck so far cutting plastics with 'wood' spade bits. I
recently needed a few 1.5" holes in some 3/4" thick nylon/polyethylene
blocks and only have a tiny Unimat DB200 lathe/mill. I had to go up in
steps as the Uni just didn't have the 'balls' to cut the 1.5" hole right
off. I was concerned about the bits 'wandering' as the point was not
cutting but with a rigid set up (using the Uni as a lathe) the holes
came out true and with an almost glass like finish. The size was bang on
to within a thou too!

I am fairly sure spade bits are available at 1.75" and they might be
worth a try (at least they don't cost much to experiment with).


Thanks for the suggestion! What speed did you find worked best?

--
---
Chris Smolinski
Black Cat Systems
http://www.blackcatsystems.com
  #8   Report Post  
Larry Green
 
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In article ,
Larry Green wrote:


I need to drill a 1 3/4 inch hole in ABS plastic. I presently have great
luck doing this with smaller holes, up to an inch or so, using a step
drill bit. I've searched around the web, and the largest dia step drill
bit I can find is 1 3/8 inch - does anyone know of one that goes up to 1
3/4 inch?



I have had good luck so far cutting plastics with 'wood' spade bits. I
recently needed a few 1.5" holes in some 3/4" thick nylon/polyethylene
blocks and only have a tiny Unimat DB200 lathe/mill. I had to go up in
steps as the Uni just didn't have the 'balls' to cut the 1.5" hole right
off. I was concerned about the bits 'wandering' as the point was not
cutting but with a rigid set up (using the Uni as a lathe) the holes
came out true and with an almost glass like finish. The size was bang on
to within a thou too!

I am fairly sure spade bits are available at 1.75" and they might be
worth a try (at least they don't cost much to experiment with).



Thanks for the suggestion! What speed did you find worked best?


I found that the slowest speed on my Unimat was too fast and had to put
a router speed controller 'inline' to reduce the speed. I have no idea
what speed it was actually running at but I adjusted the speed by 'feel'
until the bit was cutting nicely without chatter/squeal. You may have to
experiment a bit with some scrap to 'dial in' the best speed for your
application.

--
Larry Green
  #9   Report Post  
Tom
 
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Chris Smolinski wrote:

I need to drill a 1 3/4 inch hole in ABS plastic. I presently have great
luck doing this with smaller holes, up to an inch or so, using a step
drill bit. I've searched around the web, and the largest dia step drill
bit I can find is 1 3/8 inch - does anyone know of one that goes up to 1
3/4 inch?

--
---
Chris Smolinski
Black Cat Systems
http://www.blackcatsystems.com


Bradrad make step drills up to 1-1/2" but that's no consolation.
You could try one of these:
http://www.aircraftspruce.com/catalo...holecutter.php
They work well if used at the appropriate speed.

Tom
  #10   Report Post  
Nick Hull
 
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In article ,
Chris Smolinski wrote:

In article ,
"Tom Miller" wrote:

Try a holesaw. They are effective and relatively cheap.


I've tried one, and had terrible results, with a very rough edge and
melting of the plastic. Perhaps it was the particular one I used, or the
speed of the drill?


Melting means it got too hot, try cutting with ice water.

--
Free men own guns, slaves don't
www.geocities.com/CapitolHill/5357/


  #11   Report Post  
 
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I use a spray bottle of isopropyl rubbing alcohol to cool plastic cuts.
You just take little bites, enough feed to make a chip, but back off
frequently keeping everything near room temp. Be very patient; plastic
is an insulator of electricity and heat, so it takes a lot of time for
the heat to dissipate, thus the evaporative coolant, rather than a
flow-on coolant.

If you can get the cut started with a holesaw, you can finish it.
Withdraw, stop, and feel with your hand until you have a feel for the
frictional heat buildup. Patience! A 1:10 duty cycle is not out of the
question.

Open a window, of course.

  #12   Report Post  
Posted to rec.crafts.metalworking
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Posts: 1
Default 1 3/4 inch step drill bit ?

replying to Chris Smolinski, Paul wrote:
6mm-60mm Large 1/2'' Shank HSS 4241 Spiral Groove 12 Step Drill Bit Hole
Cutter. If you can be 0.07165 off a 45mm step drill bit would work. Found on
e-bay for $23

--
for full context, visit http://www.polytechforum.com/metalwo...it-397290-.htm


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