X3 6000 rpm for about 1 Dollar

[pzzamakr1980]

I got sick of the underpowered motor and a vibration I couldnt get rid of when I was using my belt drive that I made for the x3 so I went back to my noisy gear drive. I was really pissed that I was going back to stock speeds but couldnt continue having no torque and vibration with the belt drive. I use 1/4 carbide bits for my parts but I also use assorted drill bits and even 9mm drill bits were too much for the motor and it would constantly bog down and fault with even peck drilling. While I was putting everything back together I had a bit of an epiphany, what if I switch the belt pulleys. The motor pulley is 1.2 inches in diameter and the head pulley is 2 inches in diameter. In stock position you get a theoretical top speed of 2400 rpm and with drag and the gears it comes out to 2000 rpm realistically. Its actually a bit slower especially when you add cutting and holding stuff. With the pulleys switched you get a theoretical speed of 6664 rpm. Again, its a bit slower because of drag and such but still up there.
To make this conversion all you have to do is turn the head pulley down to the same size as the motor pulley and then make some adapters. I made adapters so I could easily switch back and forth at will with only a few minutes of my time. If anyone would like just post that you would like the dimensions and I will put them up.
Because I managed to ignite my gecko 201 on my z axis I havent been able to check this in practice but I did try to stop the spindle with my hand and could barely slow it down even a pinch. When I had my belt drive I could, with a bit of effort, cause the motor to fault out and stop. The only drawback with this is that the gears freaking howl. They were loud at 2000 rpm and they are even louder now. That was a major reason I went to the belt drive.
In all, because I had some scrap aluminum lying around, it cost me about a buck and an hour of my time. It would have taken me much less time but I am terrible at the lathe and I had a few screwups. This is a really simple conversion and other then having to cut one gear which is readily available through grizzly for cheap, there are no other modifications.

[philbur]

Sounds interesting. If I understand correctly what you have done is basically matched the gearing/pulley sizes to the size of the cutters/rpm you are using so that the motor is running at close to full rpm with those cutters. If this is the case then it is not necessarily a good idea to copy your gearing but only the concept of matching most used cutter sizes to gearing/pulleys. As you have trebled the top rpm presumably the lowest rpm is also trebled.

Phil

Originally Posted by pzzamakr1980 I got sick of the underpowered motor and a vibration I couldnt get rid of when I was using my belt drive that I made for the x3 so I went back to my noisy gear drive. I was really pissed that I was going back to stock speeds but couldnt continue having no torque and vibration with the belt drive. I use 1/4 carbide bits for my parts but I also use assorted drill bits and even 9mm drill bits were too much for the motor and it would constantly bog down and fault with even peck drilling. While I was putting everything back together I had a bit of an epiphany, what if I switch the belt pulleys. The motor pulley is 1.2 inches in diameter and the head pulley is 2 inches in diameter. In stock position you get a theoretical top speed of 2400 rpm and with drag and the gears it comes out to 2000 rpm realistically. Its actually a bit slower especially when you add cutting and holding stuff. With the pulleys switched you get a theoretical speed of 6664 rpm. Again, its a bit slower because of drag and such but still up there. To make this conversion all you have to do is turn the head pulley down to the same size as the motor pulley and then make some adapters. I made adapters so I could easily switch back and forth at will with only a few minutes of my time. If anyone would like just post that you would like the dimensions and I will put them up. Because I managed to ignite my gecko 201 on my z axis I havent been able to check this in practice but I did try to stop the spindle with my hand and could barely slow it down even a pinch. When I had my belt drive I could, with a bit of effort, cause the motor to fault out and stop. The only drawback with this is that the gears freaking howl. They were loud at 2000 rpm and they are even louder now. That was a major reason I went to the belt drive. In all, because I had some scrap aluminum lying around, it cost me about a buck and an hour of my time. It would have taken me much less time but I am terrible at the lathe and I had a few screwups. This is a really simple conversion and other then having to cut one gear which is readily available through grizzly for cheap, there are no other modifications.

[pzzamakr1980]

Yep, both high and low is tripled. As far as appropriate speeds for appropriate cutters go, if you are using carbide cutters the spindle speed is always the limiting factor and faster is always better. This is only true with aluminum and other soft metals only. It may be true of other harder metals but because I dont have experience with them I won't state that. Also, I have yet to check how accurate the speeds are for this system, and until I get a tach to check, take the top speed as just a theoretical max. When I can verify it I will.

[project5k]

now this is something that is of great interest to me.. i've not taken the top of my x3 apart yet to see whats in there, but if i'm getting it all right, you made up a couple adapters, and swapped the toothed pullies? hmmm very interesting.. i use very small carbide cutters, the largest of which is 1/8, and go down to 1/32.. and i know that due to spindle speed limitations, my cutting feed rates are really slow..

i would like to know more, see some pictures or something like that.. i would also like to know more about this belt drive that your talking about, did that totally eliminate the gear noise in the head? whats that all about.. cause i would be worried about turning thoes gears that fast for too long.. the bearings are already getting pretty warm, and i would think that a good portion of that is due to gears in the head creatiing some of the heat...

[S_J_H]

I tried the timing pulley swap mod about 1.5 years ago on my x3. But as you say the gears howl and the high gear speeds tend to resonate the entire machine. Also the spindle will get quite hot pretty quickly. My mill was pretty new when I first tried it and and maybe now it might work a little smoother since I have many many hours on the mill now.
Keep us updated if you notice any resonating or spindle over heating.

Steve

[pzzamakr1980]

Project, as far as it goes, 6000 rpm is still not really suitable for small cutters like what you want to use. You would be much better off with a high speed spindle like a proxxon or it's ilk. However, it is faster and it is more suitable.
SJH, the mill has quite a few hours on it from early production, before I decided to embark on the build a belt drive quest, so it is very broken in. I then used my belt drive for a good bit, at speeds approaching 7000 rpm. While it did get hot, it wasnt too bad. I did let the machine run for a few days at a progressively higher speed each day to see if the bearing would work, and only then did I run it at 7000 for production. There was vibration with the belt drive but with the gears there is very, very little. It does not affect the finish in any way. But there was nearly no noise, whereas now it's so loud I cant hear myself think. The next step is to change the gears at the spindle and see if that works. I just purchased some timing belts from econobelt so I'll be doing that conversion shortly.

[pzzamakr1980]

Okay, finally got a cheap laser tach off ebay and it seems to do the trick. The max speed of the spindle with a tormach end mill holder and a 2 flute .5 endmill was 5600. So thats about a 1000 below theoretical. I intend to change out the spindle gears to the belt drive as described in arceurotrades pdf and will see if that will speed it up at all. It should give another ten percent, plus the pulleys are aluminum, so less rotating mass, and again possibly a bit more speed. Hopefully, much less noise!

[MRM RCModels]

pizzamaker,

Could you post some pics of this mod? Even better drawings with dimentions. I would like ot do this mod on my X3 this weekend.

Thanks,

Kelvin

[pzzamakr1980]

I never made any pics or dimensions. The bore on both is the same. I just made each gear the exact same dimensions (large enough for the belt, then made a small plate to go on top to restrain the belt, and a hat shaped bottom to make the offset correct so the belt was aligned properly. I used a digital caliper to get my dimensions, and nothing was overly critical for tolerances.