How do you drill with high speed spindle.

[smart1123]

Hi all I am wondering how people drill? I am working mostly in wood with a little aluminum and using a 2.2kw Huanyang spindle which want to run between 10000-24000 rpm, this seems a little high for most drill bits and they tend to burn even when peck drilling with full retract. It's my understanding that running my spindle too slow will eventually damage it and also it loses torque at lower speeds so drill bits tend to stall if I try to slow down. To get around this I have been using bits smaller than the hole and interpolating but it seems that that gets pretty hard on the ballscrews/linear rails and also uses a lot of time when you are drilling a lot of holes (last project I did had about 400).
So... thoughts?

Thanks

Luke

Similar Threads:

• high speed spindle
• My new High Speed Spindle
• High speed spindle
• High speed spindle... how high?
• High Speed Spindle 10,000 to 40,000 rpm

[coherent]

Not much you can do other than what you are. Even 6-8k is too fast for drilling in wood with small diameter drill bits. A up cut end mill will do better than most drill bits. Increase the number of pecks and reduce the peck depth if it's burning. Speed up the plunge, don't slow it or it'll just burn worse. A quick mount for a small electric or air drill is an option. A cheap harbor freight air drill might be worth a test. If I have to drill a bunch of holes in a sheet, I have just started each hole with the spindle to mark the location and start the hole, then simply used a cordless drill to enlarge and/or complete if extreme precision isn't necessary. It's faster to finish by hand then helix ramp cut a lot of holes with a smaller bit, or peck each hole 10 times on the CNC. But then again with either of the latter, all you have to do is sit and watch!

[msimpson99]

If it is a real small diameter hole 1/8 or less I just chuck it up in the spindle or router and set it to about 5000RPM. You are not going to pull any load so you wont hurt the spindle or router.

I never peck drill with a end mill unless its soft material. If the hole is larger than 1/8" I use a n end mill and mill the hole. If its a large hole I will use a larger end mill. On harder materials I ramp as I plunge.

Here I am milling some holes in aluminum. For wood just increase the feed speed and cut depth.


Im running at 24000 RPM and a feed rate of 40IPM. With wood you will want to do tween 50-150 depending on finish.

Here I am drilling some 1/8 holes in aluminum using a standard 1/8" drill bit.

[wizard]

Hi all I am wondering how people drill? I am working mostly in wood with a little aluminum and using a 2.2kw Huanyang spindle which want to run between 10000-24000 rpm, this seems a little high for most drill bits and they tend to burn even when peck drilling with full retract. It's my understanding that running my spindle too slow will eventually damage it and also it loses torque at lower speeds so drill bits tend to stall if I try to slow down. To get around this I have been using bits smaller than the hole and interpolating but it seems that that gets pretty hard on the ballscrews/linear rails and also uses a lot of time when you are drilling a lot of holes (last project I did had about 400).
So... thoughts?

Thanks

Luke

Is this a commercial venture? If it is I'd think seriously about a low speed spindle attached to the Z axis in some manner. It sounds like you do enough hole drilling to justify the investment. 400 holes is a lot compared to many usage patterns for CNC router.

Another possibility is to try to feed the drill bit fast. You will burn at high RPMS due to rubbing and the longer it takes to drill the hole the higher the chance of burning. Your machine might not have feed rate fast enough nor the torque to do this. Depending upon the material you will want to be feeding each cutting edge a few thousands per rev., do the math and that is pretty fast with an 8k spindle.

Ultimately though you really need to have a spindle that can operate at the proper speed for the cutter and material being machined.

[Goemon]

Hi all I am wondering how people drill? I am working mostly in wood with a little aluminum and using a 2.2kw Huanyang spindle which want to run between 10000-24000 rpm, this seems a little high for most drill bits and they tend to burn even when peck drilling with full retract. It's my understanding that running my spindle too slow will eventually damage it and also it loses torque at lower speeds so drill bits tend to stall if I try to slow down. To get around this I have been using bits smaller than the hole and interpolating but it seems that that gets pretty hard on the ballscrews/linear rails and also uses a lot of time when you are drilling a lot of holes (last project I did had about 400).
So... thoughts?

Thanks

Luke

Spindles don't lose torque at lower speeds. It's the opposite. Torque is constant up to the base speed and then drops off between the base speed and the top speed. A 2.2kw 24,000 rpm spindle doesn't have much torque at any speed but that doesn't really matter for hobby woodwork.

The issue with cheap air cooled spindles at low speed is that they use shaft fans. When the spindles moves slowly then the cooling fan isn't as effective. More expensive air cooled spindles use seperate electric fans or compressed air cooling so they can be cooled equally well at all speeds.

I read that some people upgrade their shaft fan spindles by adding their own electric fans. Sounds like too much hassle to me though. Low speed drilling spindles are very cheap.

- - - Updated - - -

Hi all I am wondering how people drill? I am working mostly in wood with a little aluminum and using a 2.2kw Huanyang spindle which want to run between 10000-24000 rpm, this seems a little high for most drill bits and they tend to burn even when peck drilling with full retract. It's my understanding that running my spindle too slow will eventually damage it and also it loses torque at lower speeds so drill bits tend to stall if I try to slow down. To get around this I have been using bits smaller than the hole and interpolating but it seems that that gets pretty hard on the ballscrews/linear rails and also uses a lot of time when you are drilling a lot of holes (last project I did had about 400).
So... thoughts?

Thanks

Luke

Spindles don't lose torque at lower speeds. It's the opposite. Torque is constant up to the base speed and then drops off between the base speed and the top speed. A 2.2kw 24,000 rpm spindle doesn't have much torque at any speed but that doesn't really matter for hobby woodwork.

The issue with cheap air cooled spindles at low speed is that they use shaft fans. When the spindles moves slowly then the cooling fan isn't as effective. More expensive air cooled spindles use seperate electric fans or compressed air cooling so they can be cooled equally well at all speeds.

I read that some people upgrade their shaft fan spindles by adding their own electric fans. Sounds like too much hassle to me though. Low speed drilling spindles are very cheap.

[coherent]

Spindles don't lose torque at lower speeds. It's the opposite. Torque is constant up to the base speed and then drops off between the base speed and the top speed. A 2.2kw 24,000 rpm spindle doesn't have much torque at any speed but that doesn't really matter for hobby woodwork.
.

Just my 2 cents, but I disagree. The torque is not constant under 8k or so or above 12-14k It may have fairly consistent torque range within those optimum operating RPMs but not below or above them. You'll overheat a 24000 rpm import spindle at low RPMs if you run it slow for any extended period, load or no load and you can likely stop it with your hand fairly easily at low RPMs, Torque on these drop very quickly when RPMs are lowered outside of the optimum operating speeds unless using a much more expensive Vector drive and even this isn't always a big help depending on the VFD. If its a simple 2 pole induction motor it is not designed to run slow and the bearings aren't designed or made for low RPM loads which is why it will run hot at low RPMs. For low rpm and high torque you need a motor with more poles and stronger bearings and the right VFD seup. 6k to 8k is about the lowest RPM you want to operate at.

[Goemon]

Just my 2 cents, but I disagree. The torque is not constant under 8k or so or above 12-14k It may have fairly consistent torque range within those optimum operating RPMs but not below or above them. You'll overheat a 24000 rpm import spindle at low RPMs if you run it slow for any extended period, load or no load and you can likely stop it with your hand fairly easily at low RPMs, Torque on these drop very quickly when RPMs are lowered outside of the optimum operating speeds unless using a much more expensive Vector drive and even this isn't always a big help depending on the VFD. If its a simple 2 pole induction motor it is not designed to run slow and the bearings aren't designed or made for low RPM loads which is why it will run hot at low RPMs. For low rpm and high torque you need a motor with more poles and stronger bearings and the right VFD seup. 6k to 8k is about the lowest RPM you want to operate at.

You are confusing two issues.

It is true that shaft fan cooled spindles do not perform well at lower speeds but that is not related to torque (or where they are made). A 2.2kw spindle with .8nm of torque will have .8nm of torque at any speed up to the base speed whether it is Chinese or Colombo. If the base speed is 18,000rpm then torque will not drop of until it is higher than that speed. The issue is cooling.

If the fan is connected to the shaft then it moves slower and cools less effectively the lower the spindle speed which is why people pay more for spindles with seperate electric fans. Excess heats causes a variety of issues for motors.

I spent a long time taking advice on this issue when choosing my spindle because I had a choice between paying $950 for a rebuilt shaft fan spindle or paying $1800 for an electric fan model. I went with the electric fan model because it is for aluminum and it was rated to run anywhere from 1,000rpm up to 24,000 rpm. An otherwise identicle shaft fan model was only rated for 10,000 rpm and above.

Lower spindle speeds do not require upgraded bearings. It is higher speeds and more torque that require different bearings. My spindle has the upgraded ceramic bearings because it is a 24,000 rpm model. The same spindle with a top speed of 18,000rpm uses steel bearings. More speed generates more heat and (as it was explained to me) this can somehow end up with steel bearings getting welded to each other (or something).


You won't find any Chinese router spindles (or any other) where torque starts off low and increases as the rpm goes up. That's not how motors work. Take a look at any of the torque / power / rpm charts provides by Colombo, PDS, HSD, GMT (which is Chinese made) etc. every single one has constant torque up to the base speed and reduces after that.


None of this is a matter of opinion. If you have seen a torque chart for a spindle that shows torque increasing as the rpm increases, post a link.

[mactec54]

You are confusing two issues.

It is true that shaft fan cooled spindles do not perform well at lower speeds but that is not related to torque (or where they are made). A 2.2kw spindle with .8nm of torque will have .8nm of torque at any speed up to the base speed whether it is Chinese or Colombo. If the base speed is 18,000rpm then torque will not drop of until it is higher than that speed. The issue is cooling.

If the fan is connected to the shaft then it moves slower and cools less effectively the lower the spindle speed which is why people pay more for spindles with seperate electric fans. Excess heats causes a variety of issues for motors.

I spent a long time taking advice on this issue when choosing my spindle because I had a choice between paying $950 for a rebuilt shaft fan spindle or paying $1800 for an electric fan model. I went with the electric fan model because it is for aluminum and it was rated to run anywhere from 1,000rpm up to 24,000 rpm. An otherwise identicle shaft fan model was only rated for 10,000 rpm and above.

Lower spindle speeds do not require upgraded bearings. It is higher speeds and more torque that require different bearings. My spindle has the upgraded ceramic bearings because it is a 24,000 rpm model. The same spindle with a top speed of 18,000rpm uses steel bearings. More speed generates more heat and (as it was explained to me) this can somehow end up with steel bearings getting welded to each other (or something).


You won't find any Chinese router spindles (or any other) where torque starts off low and increases as the rpm goes up. That's not how motors work. Take a look at any of the torque / power / rpm charts provides by Colombo, PDS, HSD, GMT (which is Chinese made) etc. every single one has constant torque up to the base speed and reduces after that.


None of this is a matter of opinion. If you have seen a torque chart for a spindle that shows torque increasing as the rpm increases, post a link.

May be this will help

[coherent]

Sorry, you are correct, torque remains constant to base speed. I incorrectly used the term torque vs power or HP. I used the term torque to express a unit of power and that's not true. I think a lot of folks hear "more torque" and think more power.
The OP said his spindle stalls at low RPM. You are correct because this would be due to a lack of power not torque. When the speed of an AC motor is controlled by a VFD, HP or torque will change depending on the change in frequency. When the VFD reduces frequency and motor speed, it also reduces voltage to keep the volts/hertz ratio constant. Torque may remain constant, but HP is reduced in direct proportion to the change in speed. Torque must double if HP is to remain constant when speed is reduced by one half. Since the torque doesn't double to produce the same HP at the lower speed the OP's drill bit stalls,The reason this occurs is because the total torque produced per unit of time is also reduced because of fewer motor rotations. The differences in the cheaper import spindles vs a high quality spindle is the reason you got a spindle with ceramic bearings. Bearings, friction, fan efficiency etc will all definitely affect power and (while maybe not theoretical torque) actual torque at low rpms. As far as bearings for low rpm vs high speed... while higher speeds definitely create more bearing heat, slower speeds require bearings made for lower RPM loads. Preventing premature wear and lowering friction depends on a number of design differences. most of which effect lube distribution and wear patterns . The race design, lube type, pressure additives, separators etc are different in quality low rpm vs quality high rpm bearings . Many low-speed applications require modifications to a standard bearing, or even custom bearings. Prob not a huge difference for basic cnc spindle applications but quality lower RPM bearings are different.

[Bob La Londe]

Spiral interpolation with an end mill works very well. Not as fast as drilling, but good as long as you aren't drilling tiny holes. For drilling tiny holes... Well guess what. You might be back up in the usable RPM range (depending on the stock material) to drill with your spindle.

I have not experimented with it myself, but there is some programming for VFDs others have done to increase horsepower at lower RPM by playing with the settings. I think they are increasing the voltage at lower RPMs. I don't know how long you can run like that...