Lathemaster/RF45 belt drive conversion(hopefully)

[pete from TN]

Hey guys,
I have been hard at work on this belt drive conversion of the Lathemaster mill I am converting to cnc in my thread" Finally getting started". I intend to make an external belt drive setup very similar to the ones that people are using with apparently good success on the X2/X3 machines on the zone. I recently purchased a brand new Teco Sensorless Vector drive with 3hp capacity. This will allow me to have three phase conversion from single phase, variable frequency/speed control using mach3, reversing, and allow me to run a larger 3 phase motor. The machine is going to be setup with a two speed belt drive setup very similar to the one on the Tormach machines.

I have during the cnc conversion stripped my millhead down to the basics and in doing so realized how simple it is to dismantle. When I got it torn down I realized that a belt drive would be relatively simple. The biggest hurdle is actually finding a way to drive the spindle directly without having to machine a complicated splined coupler. This coupler will need to run in it's own bearings to offset the pressure of the belts pulling against it radially. I was planning on making a smooth bore collar and either drilling and tapping it for a large set of three setscrews to bear on the shaft as well as machine a press fit for it. This would be less than Ideal I realized after talking to some folks who are very knowledgeable about these kinds of things( thanks art)... Anyways, I decided that was not the way to go and in talking to my friend art he was looking at his belt drive machine and I at my belt driven knee mill when he came up with a great idea. The part that came on his mill that accepts the pulley for the spindle has the exact same splined shaft opening as my machine. After realizing that this might work it was a simple task to find some suitable bearings with the same OD as the bore in the upper head casting of my Lathemaster and the ID of the sleeve that comes on his machine. I was able to order that part from his parts breakdown and order the appropriate bearings for it and got them here. I then machined some aluminum spacers to fill in the gaps between the spacing of my lathemaster mill and the new drive sleeve. Then I used the same keeper rings to reassemble the coupler. This is the exact setup the machine came with only instead of being driven internally by a gear it will be driven externally on top by a pulley and belt. After getting this assembled it was an easy thing to machine some steel standoffs and an aluminum plate to support and hold the motor that I ordered yesterday. I went with a 56c motor that is brand new and runs at 1750 rpm at 60hz.

I used an old trick to get the plate holes right. I just took a piece of paper and shaded the holes on the top of the millhead onto the paper and then transfered the holes to the 3/4 inch aluminum motor plate. I took the original bolts that held the motor on and cut off the heads making them studs and drilled and tapped some 7/8" steel standoffs for that thread on one side and 3/8-16 on the other side. Then I drilled and countersunk the holes in the knee mill for some 3/8-16 shcs. Now once the motor arrives I will machine a u shape into the front of the plate to allow the pulley and belt to fit in there. I intend to secure the motor using one of the mounting holes on the left side and another on the right side in a slot to allow for belt tension. I think that should work fine but if necessary I will machine an adapter plate. I am gonna use one of the table locks that came on the machine to lock down the motor after belt tension is adjusted.

The belt ratio is still a bit up in the air right now altho I think I have settled on a 2-1 low range and a 1.5-1 high range. This coupled with the vfd's ability to run this motor at around 10hz for around 290rpm with a 2-1 ratio should get me near the 150rpm on the low end and with the motor at max freq running motor speed of around 3500 will get me 1750 or so max on low speed. Then with a 1.5-1 on the high speed I should get a max spindle speed of 5200 or so and a min of around 500 rpm.. This is all just mathematics right now but it should work out to somewhere near that. I was actually playing with my knee mill today and ran it on the highest setting of 3600rpm and man is that flying along, I cannot imagine what 5k will look and sound like on this lathemaster mill. Should be more than enough speed for my needs. If I need to go faster than that I will setup a router spindle mount and throw my porter cable in there...

I am trying to figure out wether or not to machine some new pulleys from scratch or just buy some larger timing belts similar to what Cruiser did on his Ih machine. The drive coupler has a taper fitment of the pulleys and I am also thinking I might machine that taper off and cut a keyway for it and run some timing belts. I would love to hear ideas about this but right now I am thinking just make some pulleys so I can adjust some ratios slightly if necessary. The motor mount plate will have some aluminum skirts on the sides in addition to the standoffs to keep a breaking belt from flying into my face. In the front I am planning to make a pneumatic drawbar setup similar to hoss's which should provide some shielding from a broken belt as well. I got the Tormach system tooling here now and I am eventually planning on a simple toolchanger similar to hoss's original design.

There is still much to be done here and I am hoping for a very capable machine with enough spindle speed to make for some decent material removal rates. I watch the IH mill movies at like 3600rpm and that is just amazing. My knee mill can do similar feeds and has the same max spindle speeds but my lathemaster could never hope to keep up with that still using the gear head. I also removed the quill drive to cut down on the weight of the millhead to aid in the Z rapids. I also gutted the millhead as you can see in the pics of all the shafts and gears and forks and whatnot. It is considerably lighter now. I weighed my original motor and it was like 44 lbs. I will weigh the new motor when it arrives and calculate how much weight I removed from the machine. The millhead cap is keyed or pinned for alignment which is nice. Incidentally, the nice thing about this setup is that if I chose to keep the quill drive I can do that and run the machine much the way it came with significantly greater spindle speed. Anyways, here are some pictures. I also just got a brand new handheld laser tachometer so I can really see what this works out to. My goal is to make a good running, quiet, powerful belt drive with GOOD LOW END TORQUE to spin those large drills and face mills and yet still have a reasonably high top speed for those smaller cutters and engraving.... We will see how this goes I suppose, hope this inspires others out there with the RF style machines... peace

[BobWarfield]

Pete, let me be the first to say, "That's awesome!"

I assume the sleeve you purchased to go over the splines is from one of the round column mills that have a quill? Something like part #7 in this parts list from Grizzly?

http://www.grizzly.com/images/partslists/g1005z_pl.pdf

You're on the downhill--don't stop for nothin'!

Cheers!

BW

PS A couple trivial thoughts while you're in that head:

The quill is neither very rigid nor accurate. CNC'ers benefit greatly by looking it in the up position. Most just use the stock locking handle, but you are in a position to do a little better if you wanted.

Second, I keep thinking of mounting things to the head that would be useful. For example, a broaching attachment that uses the axis motion to do the work. You don't want to mount such a thing to the spindle--it'd hammer bearings. I'd be tempted to create some mounting points on that head for such uses. I'd probably drill and ream some dowel holes for precise alignment. You could envision a variety of accessories, including that router spindle you mentioned.

[Bubba]

Bob,
That's the one! Pete and I talked about it and he went ahead and did it! I am hoping it will work out for him even though I am a little worried about the top end speed on the quill bearings.

Art

[pete from TN]

I am pretty excited about this and as I have said before I probably would not be this far were it not for the help of my pal Art.... Clever fellow that one!! I am already ahead of you there bob on the locking of the spindle inside the millhead. There is a small hole in the casting that I dunno what it was for but I see myself drilling and tapping that hole and then into the spindle to lock this thing in place. To be honest tho, I have NEVER had the spindle move on me once I locked the main spindle lock handle down and I intend to change the long chrome handle to a larger shcs for even more holding power. As far as the spindle bearings go I already have a small problem there. I was playing with the spindle carrier drive piece and found that the bearings have a tight spot in them. The last time I used the machine I was making some rather large holes in aluminum for one of my sidewheels and I think I pushed it too hard and got the whole quill rather hot. I am thinking that I may have damaged the bearing in the bottom of the quill. SO I am probably going to be replacing the bearings with some better quality and higher speed rated ones sooner rather than later. I really did not want to take that thing apart but Oh well.... NIce thing is that with the quill drive removed taking the spindle out is a trivial matter. The fellow at the local bearing house seems to think that he can help me find a much better bearing for this application.

I like the idea of accessory setups on the millhead itself. In fact I intend to eventually machine a rigid tapping drive similar to the one Hoss did on the bottom of the spindle, only mine will probably be a stepper on top of the millhead with a mount hanging off the right side for the stepper. When I need it I will just attach a belt to the spindle and setup in mach for it.. GOt lots to learn before I mess with that tho.... I dunno about a press type setup using the millhead, as heavy and rigid as it is I would be afriad it might crack something important... The lathemaster spindle has a large lower bearing housing on it that would be perfect for the router attatchement and other applications as well as the cooling ring I am going to machine for it as soon as I get this thing running....


I sure hope to get this machine working soon because I have lots of projects waiting for it. It has taken me some time to get this far but I have to admit I had a little side job in there that I am nearly completed... MY little Samurai is almost ready for the street or trail....check it out....peace

[LUCKY13]

Very nice Pete, it looks like a easy way to achive this also. You might want to keep in mind that you will probably want a power draw bar later on . It could be something to keep in mind when your making the rest of the setup.



One thing is for sure the higher RPM will help a lot and the belt drive should help even more. This is one mod I dont think you can go wrong with as long as you get it working right. The IH video's are very revealing to what can be done and I havn't seen any other mill of this size that can perform like there setup has shown to do. The whole key I feel was the higher spindle speed and the much smoother drive/gearbox they have. A belt drive should do even more for surface finish.


I am not sure about the effects of loosing weight will have. It might even be possible for it to hurt surface finish but if it does it would not take much to do something about it. The axis motor will like the lighter weight for sure.



BTW would you be interested in making a set of X & Y motor mounts to sale for a mill like yours? I need a set for mine before i can go any farther. I am ready to order my ballscrews and buy some mounts but no one offers any mounts for these mills that they will sale. Well one company does but they look pretty weak to me and with the mtors I have I need good mounts.



Jess

[BobWarfield]

Bob,
That's the one! Pete and I talked about it and he went ahead and did it! I am hoping it will work out for him even though I am a little worried about the top end speed on the quill bearings.

Art

I don't know if Pete will end up replacing the bearings (doing so would certainly up the safe speed), but just repacking them with high quality grease seems like it would greatly improve their high speed performance.

Best,

BW

[pete from TN]

Thanks for the kind words.... I am already anticipating building a pneumatic drawbar very similar to the one Hoss and others have made to work in conjunction with the tormach tooling. I have yet to get a solid design for it down tho as I am still working on the belt drive and cnc stuff... I will be honest with you about the motor mounts. I had a nice fellow on the zone machine the basic mounts for me and that was a rather huge help. Once my machine is working I would be happy to do the same for you if you will provide the materials. I know you are not too far away, bristol right? I am gonna need some time to figure out the whole cnc thing and get to where I feel like the machine is accurate and setup right. I am also sure there is another design for these mounts that will be even better than these altho I am pretty happy with them right now...

The belt drive is IMHO the only real drawback with the dovetail machines and if this design works will be something that is easily remedied. I have high hopes for a smooth running and high speed spindle setup. After using my recently sold Round column rf31 which was belt driven and now using my new Knee mill which is also belt driven I see the beauty of it and the quiet of it and even the improved surface finish on what is a slightly less rigid machine than the Lathemaster is and seemed to be able to produce better finishes and higher metal removal rates. If this works at all it will be a significant difference.....


BOb, I had not considered the better grease option, ya got any specifics for me on that one? The bearings may be dry and with the last high heat session I ran on this machine it is probably my fault. I do intend to machine a cooling ring that will allow for the flood nozzles to be where I need them and that will hopefully keep some of the main heat from hurting the bearings on me in the future. I am also hopeful that with cnc I will not be running the machine as hard as I used to manually since the machining will be done automatically and if the cutter must run around a part many times it will not be me turning the handles so I will probably not care too much... We will see soon I hope....peace

[BobWarfield]

BOb, I had not considered the better grease option, ya got any specifics for me on that one? The bearings may be dry and with the last high heat session I ran on this machine it is probably my fault. I do intend to machine a cooling ring that will allow for the flood nozzles to be where I need them and that will hopefully keep some of the main heat from hurting the bearings on me in the future. I am also hopeful that with cnc I will not be running the machine as hard as I used to manually since the machining will be done automatically and if the cutter must run around a part many times it will not be me turning the handles so I will probably not care too much... We will see soon I hope....peace

Sure!

My preferred answer on bearing questions is always NC Cams (we'll miss you old friend!). See, for example:

NCcams, bearings again

Excellent recommendations on flushing the old grease out of the existing bearings with BrakeKlean, and on possible greases to use. Note that he says to only fill the bearing 25-30%, I've heard that advice a number of places. You'll want to think about how you go about packing the bearing as well.

Or here:

more rpms for spindle motor and spindle

He recommends Kluber LDS18.

Personally, I am very curious about fabricating an air-oil mist lubricator. That's what the VMC's primarily use. You can see from the graph on my spindle page that it gives your bearings a much greater margin than grease would for higher rpms:

http://www.cnccookbook.com/CCMillBeltDrive.html

Cheers,

BW

[pete from TN]

Thanks for the links man they look like they will be helpful. Got some reading to do there.... I am still waiting for the new motor and while I was I finally got the X and Y axis motor mounts slotted and installed the motors so I am actually On axis as IH puts it. Just gotta order me some belts for the pulleys now that I have an idea what the distance between centers is gonna be. Do you guys usually set the motor in the middle of the adjustment and then take the measurement or go more to the short side a bit? peace

[BobWarfield]

Pete, that Kluber grease is apparently awesomely expensive and they'll make you buy more than you need. There is a cheaper Kluber grease available in 50g tubes for the snowmobile crowd. Check out this thread for more on spindle bearing grease:

http://bbs.homeshopmachinist.net/arc...p/t-29658.html

RE the belt fit:

FWIW, the IH factory kit has very little slot room on the motor mounts to adjust the fit. You have to tilt the motor and lever it into place (can be done by hand, don't envision crowbars) to get it to fit. The belts are nice and tight and presumably less likely for things to slip loose.

OTOH, since I re-engineered my pulleys on 2 axes to fit my new servos, I wound up with the wrong sized belt the first go round.

BTW, ordered my Grizzly spline hub part yesterday. I'll be following close behind in your footsteps!

Cheers,

BW

[pete from TN]

I am surprised that they IH setup is not more adjustable. I machined mine to have nearly an inch of travel for belt stretch and also to make it easier to get a fitting belt the first time. Then would you say that you should go short or in the middle of travel then?

Glad to hear that you got the coupler. I bought mine from MSC in Atlanta for the RF31 machine Art has. I think the fellow said it was the last one they had? DUnno why that would be. Is your bore the same as mine is? I think it was like 68mm OD and then 45mm ID. I can check but yours may be slightly different. I am hopeful that this design will be simple and rugged but time will tell... Got any ideas which way you are gonna go with a drive belt? I cannot decide wether to order some timing pulleys and a belt or machine my own using a v belt setup. If I make my own it is time but allows some flexibility and I can make more if necessary but if I but It I will get done faster.... peace



Lucky man I was thinking that if you want someone to machine your mounts for you maybe we can trade work. I am gonna probably need some electrical help with the controller unit and I see that you have yours setup pretty nice already. Is your setup running and tested already? Peace man

[pete from TN]

I just got home and found that my new spindle motor arrived today. It looks real nice and the good news is that it actually weighs about three pounds less than the factory motor despite being nearly twice the horsepower. It is a 56c frame and I was able to machine the motor mount plate to accept the new motor pretty quickly with the new knee mill. I slotted the plate for the shaft to ride thru and then machined a large flat area to accept the little round lip on the face of the motor. I was planning on a pivoting belt adjustment using one of the screws on the motor face as the pivot but after setting it up on the plate I do not think that will be enough travel for belt adjustment. SO I am now probably gonna slot two holes opposite each other on the sides of the plate and install two of the handle screws that used to lock the axes on the mill to tighten it down. It is pretty easy to slide the motor back against the belt tension from the front and then tighten one pretty good then snug up the other I suppose. I am also kinda happy that the motor is considerably narrower than the factory cast motor so I will be able to adjust with room to spare. Now I gotta machine those slots and thread the hand screws 3/8-16 to fit the motor and get to some pulley machining. The Teco Vector unit came with a CD instruction manual which I have not gotten to watch yet but that is pretty cool if ya ask me. I am hopeful it will make installing this bad boy an easy chore. Sounds like a high speed spindle and belt drive are right around the corner. Still have work to do on the cnc conversion electronics and order my timing belts finally but so far so good. I also spent some time playing with my ballscrew mounts and fine tuned the adjustment on each to ensure a bind free travel. I thought I had the Z working great but I cannot drive it with my fingers due to the gravity and weight of the Z slide but I was running it up and down with my cordless drill and decided to set the clutch to a light setting on the drill and found it slipped near the top. I took it back apart to find that it was off a slight bit to the left which was making it a little tighter near the top of the travel. Glad I caught it before I ran this thing a whole bunch. Anyways here are some pics....peace