So....now a few more questions!

At least initially, my X3 will be limited to 2000rpm. From what I have read, Aluminum should have a surface cutting speed of 250-350 fpm.

If I aim for the low end of this (250fpm), then @ a maximum 2000rpm, aren't I limited to 1/2" or larger end mills?

I know that some people have gotten their X3's running at 6000rpm, which would let me go as small as about 5/32" end mill and still maintain 250fpm Surface Cutting Speed.

Thanks!

-Caleb105-

So....now a few more questions!

At least initially, my X3 will be limited to 2000rpm. From what I have read, Aluminum should have a surface cutting speed of 250-350 fpm.

If I aim for the low end of this (250fpm), then @ a maximum 2000rpm, aren't I limited to 1/2" or larger end mills?

I know that some people have gotten their X3's running at 6000rpm, which would let me go as small as about 5/32" end mill and still maintain 250fpm Surface Cutting Speed.

Thanks!

-Caleb105-

Actually, for HSS cutting aluminum 400-600 SFPM is more typical, but you can't get there with only 2K RPM, so your feed rates with small cutters will be quite slow. Anything you can do to increase spindle speed will increase productivity.

Regards,
Ray L.

So am I correct that I should be using at least a 1/2" end mill?

What do people use to machine their ballnut/motor/bearing mounts when they first get their mills?

Thanks!

-Caleb105-

So am I correct that I should be using at least a 1/2" end mill?

What do people use to machine their ballnut/motor/bearing mounts when they first get their mills?

Thanks!

-Caleb105-

Well, even a 1/2" endmill wants to be going faster - I usually use about 3200 RPM in aluminum. But your spindle power and rigidity become bigger and bigger factors the larger the tool you use. Most people do the bulk of their work with 1/4-3/8" tools on X2s and X3s. You just need to scale the feedrate down by the RPM you *can* achieve. The most important thing is to maintain an adequate chipload, or tool life will suffer.

Bearing pockets, etc. can be cut using a rotary table or boring head. They can also be done on a lathe.

Regards,
Ray L.

Well, even a 1/2" endmill wants to be going faster - I usually use about 3200 RPM in aluminum. But your spindle power and rigidity become bigger and bigger factors the larger the tool you use. Most people do the bulk of their work with 1/4-3/8" tools on X2s and X3s. You just need to scale the feedrate down by the RPM you *can* achieve. The most important thing is to maintain an adequate chipload, or tool life will suffer.

Bearing pockets, etc. can be cut using a rotary table or boring head. They can also be done on a lathe.

Regards,
Ray L.

I know that I SHOULD be running at MORE than 2000rpm, but I CAN'T!

Also, the feedrate won't have anything to do with the surface cutting rate.

So....are you trying to tell me that people use a 1/4" endmill and are milling their aluminum with 130fpm surface cutting speed?

-Caleb105-

I know that I SHOULD be running at MORE than 2000rpm, but I CAN'T!

Also, the feedrate won't have anything to do with the surface cutting rate.

So....are you trying to tell me that people use a 1/4" endmill and are milling their aluminum with 130fpm surface cutting speed?

-Caleb105-

Keeping the chipload in the correct area is important. You slow down the feed rate to "keep up" with the lower spindle. You are focusing on the SFPM only. Since you can't get the recommended one you adjust feed down so as to keep chipload consistent.

Keeping the chipload in the correct area is important. You slow down the feed rate to "keep up" with the lower spindle. You are focusing on the SFPM only. Since you can't get the recommended one you adjust feed down so as to keep chipload consistent.

Sigh....

I know that both the SFPM and IPM are both dependent on RPM. However, they are not directly related to each other.

What I am asking is....How are people dealing with lower SFPM? Are they just milling AL at 130fpm and praying that it doesn't gum up their endmills?

Sigh....

I know that both the SFPM and IPM are both dependent on RPM. However, they are not directly related to each other.

What I am asking is....How are people dealing with lower SFPM? Are they just milling AL at 130fpm and praying that it doesn't gum up their endmills?


"Are they just milling AL at 130fpm and praying that it doesn't gum up their endmills?" - It's either that, or figure out how to increase spindle RPM. Ain't no other options.

Regards,
Ray L.

And does that low of a SFPM have a negative effect on surface finish?

And does that low of a SFPM have a negative effect on surface finish?

Nope. Just makes your job take a lot longer.

Regards,
Ray L.

I know that I SHOULD be running at MORE than 2000rpm, but I CAN'T!

Also, the feedrate won't have anything to do with the surface cutting rate.

So....are you trying to tell me that people use a 1/4" endmill and are milling their aluminum with 130fpm surface cutting speed?

-Caleb105-

The SFPM is the cutting speed recommended by the manufacturer of the Endmill in an industrial manufacturing environment.
Meaning that this speed will be a good balance between Toollife and Metal removal rate.
In a hobbyshop where cost of Endmills may be rated a little higher and manhours a little lower it can make perfect sense to derate the SFPM.
The longest Toollife may be well below of the manufacturers recommended SFPM.

I'm regularly using 1/32" endmills on my x3, and while it does take for ever to run a complete job, it does work, and i dont have any gumming issues... good flood coolant is my thinking as to why i have been getting away with it...

so what about upgrading the spindle motor? surpluscenter.com has motors and controllers, you could buy the parts for around $100, and machine the mounts yourself. also a good time to eliminate the gearbox and switch to a direct belt drive, correct?

I'm actively looking for the upgrade that makes me happy as we speak.. or, well, type, you know what i mean.

yea, i really wanna upgrade my spindle, and i hadn't heard of that site, so thats my next stop.. I was actually looking at using a 6HP compressor rated motor that i have at the house, plenty of power, just have to set up some pullys...

eh, its just a thougt.. the only reason i havent done it yet is thats a honk'n big motor, and its very heavy...

I was looking at this motor:
http://surpluscenter.com/item.asp?UID=2009021615400649&item=10-2436&catname=electric

controlled by this controller:
http://surpluscenter.com/item.asp?UID=2009021615400649&item=11-2269&catname=

the specs don't match exactly, so the motor would run slightly slower I would imagine (probably closer to 6500 rpm). Once you remove the stock X3 motor and gearbox parts, and install a new motor with pulleys, the overall weight of the head might be reduced as well.

i think the gearhead is the speed limiter on the x3. i think using the stock motor and switching to belt drive would be enough to get the speed up to at least 3500rpm. above that and you start needing to take into acount bearings and spindle balance and runout which may or may not be that good on the stock x3. experimenting with pulleys to find the limit is easily done though.

true true, now when you are saying switch to belt, isnt it already belt drive from the motor to the input of the geartrain? so where or what would i be changing? has anyone thought or done something about possibly driving the spindle/quil directly and just bypass all the gears?

true true, now when you are saying switch to belt, isnt it already belt drive from the motor to the input of the geartrain? so where or what would i be changing? has anyone thought or done something about possibly driving the spindle/quil directly and just bypass all the gears?

I mean change the pulley ratio on the belt drive, to speed up the spindle. Put a large pulley on the motor, or a smaller one on the head, and the spindle speeds up. You'll lose low-end torque, but I doubt that's an issue, unless you bore a lot of large holes with a boring head, or use a face mill.

Regards,
Ray L.

true true, now when you are saying switch to belt, isnt it already belt drive from the motor to the input of the geartrain? so where or what would i be changing? has anyone thought or done something about possibly driving the spindle/quil directly and just bypass all the gears?

x3:
http://www.mini-lathe.com/X3_mill/X3rvw/gears1.jpg

what im saying is the gears probably cant handle much higher than 2000rpm (and will be very noisy as well).

superx3:
http://x3pulley.com/Picture%20Medium/IMG_0091%20(Medium).jpg

ideally you want the belt going right to the spindle - no gears. im not sure how much effort is involved in converting... but well, you have a milling machine to make brackets :p

I was looking at this motor:
http://surpluscenter.com/item.asp?UID=2009021615400649&item=10-2436&catname=electric

controlled by this controller:
http://surpluscenter.com/item.asp?UID=2009021615400649&item=11-2269&catname=

the specs don't match exactly, so the motor would run slightly slower I would imagine (probably closer to 6500 rpm). Once you remove the stock X3 motor and gearbox parts, and install a new motor with pulleys, the overall weight of the head might be reduced as well.

I suspect that motor won't make enough torque to turn the spindle without over heating. I had a similar motor from there that i tried on my x2 head and it sparked like mad (brushes)and got up to about 180 degrees within 5 minutes - the mill head was on the table at the time for testing, so no load aside from the spindle itself - not even a tool or collet in the spindle. The motor I had was similar in size, but lower rpms (rated 2.5hp and 6700 rpms at 130v IIRC). It had no torque!! - it made 10k rpms at the spindle after it got going, but I could grab the spindle and trip the circuit breaker while stalling it - not very impressive at all. I suspect that motor would be even worse, with its higher rpms.
The stock x3 motor did much better under the same circumstances, though it was still inadequate for my needs(got too hot too fast when turning the spindle at 7k or so rpms). The x3 spindle and head probably takes more nuts than the x2 head to turn, so I would expect even worse results on an x3(never seen and x3 in person, so this is speculation, but I assume it is slightly larger and requires more power to do the same work vs an x2 head).

ok, so let me make sure i understand what i'm looking at, (i've never had the top end of my mill apart)

the motor spins the belt, the pully is on a shaft that goes down into the head to the geartrain(the high and low) that spins the shaft in the middle of the picture, turns the right gear, which spins the spindle...

is that pretty much it?

so if i were to change it around so that it looks more like the super x3, remove the geartrain down inside the head, and then have a second pully above the back one as pictures, and run the motor belt to that, it would reduce the gear noise, cause there wouldnt be any gears, and then i could change pully sizes as i see fit....

so.. how much work is it to get inside the head?

its either that, or i could just change the gear thats on the spindle to a pully,(like the superx3) and run the motor directly to that....

ok, so let me make sure i understand what i'm looking at, (i've never had the top end of my mill apart)

the motor spins the belt, the pully is on a shaft that goes down into the head to the geartrain(the high and low) that spins the shaft in the middle of the picture, turns the right gear, which spins the spindle...

is that pretty much it?

so if i were to change it around so that it looks more like the super x3, remove the geartrain down inside the head, and then have a second pully above the back one as pictures, and run the motor belt to that, it would reduce the gear noise, cause there wouldnt be any gears, and then i could change pully sizes as i see fit....

so.. how much work is it to get inside the head?

its either that, or i could just change the gear thats on the spindle to a pully,(like the superx3) and run the motor directly to that....

I've seen a mill where the pulleys and belt bypass the gearing - the gear to drive the spindle was romoved.

http://s109.photobucket.com/albums/n48/S_J_H/x3%20mill/?action=view&current=Stevie252-1.jpg

I'm sure this guy is a member of these forums. I don't know how well this worked for him but I don't know why he hasn't chimed in.

Rick

take a look at my high speed spindle thread, i swapped the pullys between the input of the gearbox, and the motor, ended up with 2500 on low gear, and 5100 on high...

i dont know about the v belt so much, but if i decide i dont like the results of what i have now, i'll try something like that... i would think that if i were to do something like that, i would probably like it better, and it'd be quieter, and have more cutting torque cause i'm not wasting some spinning the gears...

Sigh....

I know that both the SFPM and IPM are both dependent on RPM. However, they are not directly related to each other.

What I am asking is....How are people dealing with lower SFPM? Are they just milling AL at 130fpm and praying that it doesn't gum up their endmills?

You're spinning your wheels! My advice: don't get lost in the books and formulas until you've made some chips. All of this stuff is about ideals, when pretty much nothing we do is ideal. Theory tells you what ought to work, practice tells you what actually does. One thing is for sure that you can get sucked into spending all your time fidgeting with your tools and none actually making parts.

I cut plenty of aluminum on my X1 which was limited to ~2000RPM and started to cry if I tried using tools much bigger than 1/4". I stuck to 3- and 4-flute mills and used feeds of 10-12IPM mostly due to lack of power, but ran up to 15IPM with light cuts. I would not lose sleep over tool life just yet.

i could be way off base but i think when you start talking about bypassing gears for the direct drive, it might be easiest to just get a different mill?(or pull a full blown hoss router from the side or w/e). from my very simple knowledge of how the head works, (excuse the lack of proper terminology here :p: ) but the spindle is connected to a series of gears which is later turned by a belt by the motor, which we know. But even if you bypassed the gears another problem that my simple mind thinks is that you would still need the torque to spin the gears, just you would basically be going motor -> spindle -> gears instead of motor -> gears -> spindle which somewhat defeats the purpose no?

This is a question so please don't flame :)

actually thats not quite right.. if i decide to bypass the gears, and go from the motor directly to the spindle, i will take the gear off the spindle such that it no longer spins the gearbox, its as simple as sliding a gear off a shaft.

then the gears arent in the equasion at all, and thus theres no torque lost in spinning them.

actually thats not quite right.. if i decide to bypass the gears, and go from the motor directly to the spindle, i will take the gear off the spindle such that it no longer spins the gearbox, its as simple as sliding a gear off a shaft.

then the gears arent in the equasion at all, and thus theres no torque lost in spinning them.

True! But since the gears were there in the first place to INCREASE torque at the spindle, (And you are not matching that gearing with your pulley ratio) even a 1:1 pulley ratio will deliver less torque to spindle. OVER driving the spindle, to even faster speed, reduces tool torque even further.

There is probably a torque adjustment pot on the motor board, and this may help some, but you WILL be trading torque for RPM. There is no free lunch.

CR.

I have a couple of those controllers and love them. The key is to get a decent motor without so much speed. I am running a much nicer motor on my mill at 220 VAC with this controller. Probably getting every bit of 2HP out of it.
On my lathe, the motor looks very similar to the mill, but is rated for less voltage. I run it on 120 VAC. My mill gets 6600 RPM top end.
Lathe at 4200 though I never run it that fast for cutting.
These controllers are fantastic an well worth the price. Get the heat sink too. There are onboard pots to adjust every aspect of it's control.
You cannot bog my mill at all and only doing something crazy will start bogging the lathe.
Don't rule out treadmill motors, just choose the right ones.

http://www.cnczone.com/forums/attachment.php?attachmentid=58115&d=1208791493


http://www.cnczone.com/forums/attachment.php?attachmentid=73338&d=1231677075

http://www.cnczone.com/forums/attachment.php?attachmentid=72586&d=1230727278



I was looking at this motor:
http://surpluscenter.com/item.asp?UID=2009021615400649&item=10-2436&catname=electric

controlled by this controller:
http://surpluscenter.com/item.asp?UID=2009021615400649&item=11-2269&catname=

the specs don't match exactly, so the motor would run slightly slower I would imagine (probably closer to 6500 rpm). Once you remove the stock X3 motor and gearbox parts, and install a new motor with pulleys, the overall weight of the head might be reduced as well.

my reasoning for going with one of those motors and ditching the gears is the fact that I have read several conversion threads where the stock X3 motor controller either died, or wouldnt play nice with Mach3. Also, The regular X3 is $400 cheaper than the Super X3 (I'm looking at the Grizzly version), and converting to CNC eliminated the majority of the SX3s advantages.

CR, your right, and if i needed a bunch of torque for large cutters then you'd be right, but in my case the biggest cutter i use even occasionally is 1/4, maybe 3/8, and 99% of my work is with 1/8 and smaller, so the torque requirements are pretty low. Its my speed thats really suffering, thats why i'm "gearing up"

I think i can afford to loose some torque so long as i can gain rpm's

I will keep an eye on it tho, and if i notice that the spindle is slowing when cutting then i will know that i'm reaching that point where torque is becomming an issue.

The controller mentioned from Surplus center has a torqu pot as well as an IR pot. This later tries to maintain constant speed when cutting. Does a great job of it as well.
I can use an 1.25 indexible face mill at .05" DOC in mild steel and 4000 rpm with no bogging at all. Granted I am using 220 volts

I agree with Project. I went to a belt drive with a fixed gear ratio. Using a single ratio I can easily drill up to 1/2 in steel as deep as I want. I can use a face mill to surface a block, and then I can belt out 7000rpm for using the tools I use 98% of the time, 1/4 or less. The x3 does not play well with big endmills and I can remove a great deal of material in a short time with higher feedrates and deeper depths of cut with small cutters.

Also, my mill is whisper quiet at even 7000rpm. When (not if) the stock bearings fail, something nicer will go in and the mill will even be better.

I used a bit nicer of a dc drive and big motor, but it didn't cost me much more than the treadmill motor and surplus drive, and with it I couldnt be happier.

The controller mentioned from Surplus center has a torqu pot as well as an IR pot. This later tries to maintain constant speed when cutting. Does a great job of it as well.
I can use an 1.25 indexible face mill at .05" DOC in mild steel and 4000 rpm with no bogging at all. Granted I am using 220 volts

Hey Lee,

I was curious and wanted to know how much power was actually needed to make various cuts, so I did some checks today and got some numbers that might interest you.

At 4200 RPM, 40 IPM, my 2" face mill at .1 DOC, 90% stepover, is using right on 3 Hp in Fortal (basically 7075 Alu), so I think you're bang on the money with the comment about getting your 2 Hp out of it...

What feed rate are you using for your 1.25" face mill in steel? How is the finish?

Best regards,

Jason

Hey guys, I have a quick question. How successful is the IR pot on that drive. Is it comparable to a tach feedback drive that can compensate knowing the actual speed? Also, what does the torque pot do. What is it limiting or not?

Hey guys, I have a quick question. How successful is the IR pot on that drive. Is it comparable to a tach feedback drive that can compensate knowing the actual speed? Also, what does the torque pot do. What is it limiting or not?

The IR adjustment is a gain control on the current-based voltage feedback. When current increases, the controller assumes this is a result of increased load, which it assumes will cause a drop in speed, so it increases voltage to bring the speed back up. The adjustment basically controls how much the voltage will be boosted as a function of current. It is essentially an open-loop correction, so it is nowhere near as accurate as actual tach feedback, but when properly adjusted works more than well enough. This is a VERY common feature on DC motor drives, though on many it is a fixed value, not adjustable.

Regards,
Ray L.

Thx Himmy. So would a drive that has IR feedback have tach feedback or would the tach feedback make it unnecessary?

Thx Himmy. So would a drive that has IR feedback have tach feedback or would the tach feedback make it unnecessary?

No, IR is a way of avoiding the expense of a tach.

Regards,
Ray L.

I wouldn't say the IR is accurate enough for threading, but is sure does help maintain speed.
I am pretty sure the torque pot increases the amps. There are steps to adjusting all these pots that are in the PDF manual that can be found online. If you take your time, you really can get a nice motor to purr. Like my old chevy truck, I adjust the timing by ear. You know when you got it just right. It just purrs. ;)


Jason, I run the flycutter at 15 IPM. I was really impressed to get so much power and control for about $200 total for the motor, it's controller and a speed control. I didn't land on this setup to start with though. I initially tried a different motor controller and speed controller and had pretty poor results. Better than the X2 OEM, but still not what I was looking for.