Shaft RPM for notching tubing & 1/2"+ bits [Archive]

yurtle

03-13-2002, 06:33 PM

Read the old drill press thread. This thing is on sale at HF right now:

HF Drill press (http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=43389)

$179 sounds pretty good for this setup, considering my 14" delta just puked. It was a 1/2" model, and marginal for 1/2 bits in mild steel.

This will be used to notch up to 1 3/4 tubing. What speed do you want at the spindle for this? And no, I don't want to use a grinder. That is what I have been doing and it sucks. I need more precision in determining the final cut-to length, and if I leave any gaps in the fishmouth my crappy welding skills result in big holes.

Thanks

Brian

BTW - went by HF, this thing feels pretty nice. solid unit, has a lube feed bottle and drain table.

bgreen

03-13-2002, 09:24 PM

I agree with Burbin, I would have said 130 RPM

Here is one for ya, if you like your calculator. (I take mine in the Sh!ter with me) :D :D

((C.S. x 12)/(Pi x DIA))= RPM

Cutting Speed x 12, divided by Pi x the diameter or tool, = the recommended rpm's

C.S. = Cutting speed (found in chart)
PI = 3.14
DIA = Diameter of tool

Cutting Speed

High Speed Steel Carbide

For 4340 using High Speed Steel - 60 using Carbide - 230
For 1018 using High Speed Steel - 90 using Carbide - 350
For Alum using High Speed Steel - 400 using Carbide - 1200
For Cast using High Speed Steel - 70 using Carbide - 300

example:
1/2" High Speed Drill into 4340 should turn 458 rpm.

((60x12)/(3.148.5)) = 458 RPM

These are just starting points. By no means is this exactly the rpms you should run. Its just a place to start from. I use this at work all the time. (every day) alot of it is going to depend on how rigid your setup is and the tool geometry.

Generally when cutting steel with HSS tools I watch for color in the chips. If the chips are turining gold you are probably pusing your luck. If they turn blue, your high speed steel tool (Drill) will not last. With carbide tools blue chips are good, but sparks are bad. :D

Use lots of oil, and don't let the tool dwell for long. In alloy, stainless, and high carbon steels dwelling will cause "work hardening" and you will have to drill in from the opposite side to cut through it. Major bummer. Using the proper rpm will help you to drill the straightest possible holes if you have to go very deep.

kind of got off the topic of hole saws :rolleyes: but the above directly relates. I thought this might be a good place to talk about drilling in general. Again, just a place to start, so don't take this as set in stone.


Pirate4x4.Com > General Tech > General 4x4 Discussion > Shaft RPM for notching tubing & 1/2"+ bits PDA : Shaft RPM for notching tubing & 1/2"+ bits yurtle 03-13-2002, 06:33 PM Read the old drill press thread. This thing is on sale at HF right now: HF Drill press (http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=43389) $179 sounds pretty good for this setup, considering my 14" delta just puked. It was a 1/2" model, and marginal for 1/2 bits in mild steel. This will be used to notch up to 1 3/4 tubing. What speed do you want at the spindle for this? And no, I don't want to use a grinder. That is what I have been doing and it sucks. I need more precision in determining the final cut-to length, and if I leave any gaps in the fishmouth my crappy welding skills result in big holes. Thanks Brian BTW - went by HF, this thing feels pretty nice. solid unit, has a lube feed bottle and drain table. Hypoid Drive 03-13-2002, 07:41 PM 80 - 150 RPM for tube notching if you want the hole saws to last:D bgreen 03-13-2002, 09:24 PM I agree with Burbin, I would have said 130 RPM Here is one for ya, if you like your calculator. (I take mine in the Sh!ter with me) :D :D ((C.S. x 12)/(Pi x DIA))= RPM Cutting Speed x 12, divided by Pi x the diameter or tool, = the recommended rpm's C.S. = Cutting speed (found in chart) PI = 3.14 DIA = Diameter of tool Cutting Speed High Speed Steel Carbide For 4340 using High Speed Steel - 60 using Carbide - 230 For 1018 using High Speed Steel - 90 using Carbide - 350 For Alum using High Speed Steel - 400 using Carbide - 1200 For Cast using High Speed Steel - 70 using Carbide - 300 example: 1/2" High Speed Drill into 4340 should turn 458 rpm. ((60x12)/(3.148.5)) = 458 RPM These are just starting points. By no means is this exactly the rpms you should run. Its just a place to start from. I use this at work all the time. (every day) alot of it is going to depend on how rigid your setup is and the tool geometry. Generally when cutting steel with HSS tools I watch for color in the chips. If the chips are turining gold you are probably pusing your luck. If they turn blue, your high speed steel tool (Drill) will not last. With carbide tools blue chips are good, but sparks are bad. :D Use lots of oil, and don't let the tool dwell for long. In alloy, stainless, and high carbon steels dwelling will cause "work hardening" and you will have to drill in from the opposite side to cut through it. Major bummer. Using the proper rpm will help you to drill the straightest possible holes if you have to go very deep. kind of got off the topic of hole saws :rolleyes: but the above directly relates. I thought this might be a good place to talk about drilling in general. Again, just a place to start, so don't take this as set in stone.