Spindle Idea

[MikeAber]

Ok Speedre,

No worries mate!

Look at Jon's pictures in his photo gallery and the earlier post in this thread. My pulley setup will be more difficult. I plan to have the pulleys and belt inside the motor mount plate. I won't know how long my belt will be until I do a mockup of the assembly and make measurements. I am in the neighborhood of 18 to 20 inches on belt length but I am using 2+ inch diameter pulleys. The drive belts start at 15" and go all the way up to 42" in the size I chose.

As you are using less horsepower you could probably use a 1/4" or 3/8" belt to drive the spindle and the cost would be less as well. I will take a look at that for you and make some observations for you if you wish. Measure your motor shaft diameter and let me know if you want me to do that for you.

Mike

Your drawing is interesting, OK 8" long. Looking good!

[MikeAber]

Speedre,

L Series 1/2" wide Timing Belts and Pulleys.
10 teeth on motor pulley 20 teeth on spindle pulley = 2:1 turns ratio = 3000 rpm max.
15 teeth on motor pulley 20 teeth on spindle pulley = 1.5:1 turns ratio = 4000 rpm max.
20 teeth on motor pulley 20 teeth on spindle pulley = 1:1 turns ratio = 6000 rpm max.
MSC & McMaster-Carr both stock these 25.00 for the 20 tooth, 10.00 for the 10 tooth, 15.00 for the 15 tooth and a 21" belt is less than 10.00.

Mike

[SPEEDRE]

Thanks again Mike. I'm going to break down my mini this weekend so I should have the shaft info Mon. I will get it to you then. This is a learning process for me, I must have slept that day in class lol heh.

[MikeAber]

The timing belt pulleys and belleville spring washers were delivered yesterday so I worked on the those last night. I was surprised at how large and well made the pulleys were.

They don't make a 17mm quicklock motor shaft bushing so I ordered a 5/8" bushing and bored it to .670" .001" over the motor shaft diameter. I had to fuss with motor pulley a lot to get things where I wanted them. It was worth the effort as the tapers on the bushing and in the pulley locks the pulley on the shaft with no damage and it's easy to change pulley sizes.

I counter bored the holes for the pulley mounting screws to keep them away from me and work on the table, then rounded all the edges. I didn't like the shiny polished finish on the drive sleeve and pulley so I cold blued them.


The spindle drive pulley was bored to 1.648" (.003" under the diameter of the spindle drive sleeve). Then I used the precision turning tools to increase the inside diameter to 1.6495" with a .0005 taper to the right side. The picture shows I can barely get the spindle drive sleeve started into the timing belt drive pulley then I pressed the pulley onto the spindle drive sleeve with my precision bench vise and socket combo. The drive pulley and drive sleeve are steel, the interference fit is .0015" - it's not going anywhere.

There are two photos of the spindle and if you look carefully you will see a difference between a light preload condition - about 10 pounds- and a heavy bearing preload - about 500 pounds -.


Almost Done! Just need to make the motor mount, make a mount to mount the motor to the spindle and install the drive belt.

Mike

[MikeAber]

Aaron at Industrial Hobbies sent me a new oil level glass for my Industrial Hobbies mill to replace the one that self destructed at no charge! It arrived on Friday, so I put the machine back together and topped off the oil then back to work.

Getting everything to work together requires the motor to fit in the spindle profile; therefore the motor mounting system was next.

The modified spindle housing is 3.5” deep, I needed a motor no larger than that and my motor controller can’t control any more than 1.5 horsepower anyway so the 1.5 horsepower 5100 rpm treadmill motor seemed the way to go, at $29.00 I could afford to experiment a little.

I cut down the motor’s front bearing plate from the original 7” diameter to 3.55 “square. Then I machined a 3.55” square .5” thick spacer with a 2.5” hole in the center to match the hole in the motor plate and mounted the plate to the spacer with 4 10-24 SHCS and milled the surfaces to create a 3.5” square mount. After a test fit of the timing belt pulley I decided to bore the center hole out to 2.75” to increase the air flow around the pulley. I removed the motor armature from the motor housing, clamped the housing to my mill table and removed the welds from the mount to the housing with a 3/8” carbide end mill, took the rest of the welds off the housing with a mill file, cleaned up all the housing surface imperfections with an orbital sander, primed and painted the housing.

Now for the hard part; the motor mount/timing belt cover. This is probably the most complex part I have ever made! I needed a safe, sturdy mount for the motor that would provide for adjustment of the belt, hide the timing belt and pulleys and have a clean look as well as functionality. This is what I came up with. The cover/mount took over 6 hours to machine and fit to the spindle. Those special nuts I made to allow adjustment of the belt were a pain to make.

What’s next? I need to order a 15” timing belt, make a motor shaft ½-13 LH end nut, a cover for the bottom of the belt cover and a spindle lock for tool changes. I'm eager to get this going so cadcam can do this stuff.

Mike

[SPEEDRE]

Hi Mike I took apart my mini today so i can have it cut down. At first I did'nt see how the motor will turn the shaft, but after viewing your pics I understood. Good job BTW, looking good. On the top there is a large nut with slots in it, how did you get it off so you could mount the pulley? I assume that the hieght of the pulley will take up the space of the stock spacer that's right under the big nut, correct? If so, will that dictate the width of the belt also. Next question,( I got a million of 'em) lol, how is the spindle pulley secured to the shaft? Have you made an interference fit and pressed it on? One more, the motor that comes with the mini is 4/5 hp , 6000 rpm, is a heavy puppy if I stay at 1:1 and offset the drive like you did how do you think the weight will affect the Z carriage? I know this is alot of questions but I'm here to learn. Thanks Mike..

[MikeAber]

Hi Speedre,

I used a spanner wrench to remove the spindle nut. It is a left hand thread.

The spindle drive pulley is press-fit over the spacer under the spindle nut. I measured the spindle spacer in my spindle at 1.651”. I bored the spindle drive pulley to 1.648" (.003" under the diameter of the spindle drive sleeve). Then I used a piece of 320 grit silicon carbide paper wrapped around a piece of drill rod to increase the inside diameter to 1.6495" with a .0005 taper to the right side. This is known as a lead-in diameter. The picture shows I can barely get the spindle drive sleeve started into the timing belt drive pulley then I pressed the pulley onto the spindle drive sleeve with my precision bench vise and socket combo. The drive pulley and drive sleeve are steel, the interference fit is .0015". A permanent press-fit is considered from 0.0015” to 0.0025” interference for the objects to be put together. Objects that are press-fit together may be pressed apart again, but it is considered a permanent assembly. You will need to measure your spindle spacer and remove any imperfections that may interfere with the pressing of the parts together. This allows us to make adjustments to where the pulley is on the spacer which is now a “spindle drive sleeve”. There is a good picture of the drive pulley mounted on the spindle drive sleeve there. (The black pulley)

“the motor that comes with the mini is 4/5 hp , 6000 rpm, is a heavy puppy if I stay at 1:1 and offset the drive like you did how do you think the weight will affect the Z carriage?”

I don’t know anything about your machine; I do not have enough information to answer this question. How much does a 3.5 horsepower router weigh? I haven’t weighed this assembly yet; I am guessing it weighs 20 pounds.

Please go to my photo gallery to look at the larger pictures of the project it may help. http://www.cnczone.com/gallery/showgallery.php?cat=9016

Ask more questions as needed.

I highly recommend this book:
A really good book for hobbyists like me and it includes a demo version of MASTERCAM is:
Machining and CNC Technology by Michael Fitzpatrick
ISBN 0-07-829860-1

Mike

[SPEEDRE]

Mike, I tried to find timing pulleys with hubs of around 2.00" dia. but could'nt, where did you get the drive pulley ?. So press fit the drive pulley onto the spacer and reassemble, correct?. As soon as I get the info to oreder the pulleys I'm going to cut chips, wish me luck. Thanks Mike. Gee we work well together,lol

[MikeAber]

Hi Speedre look at these:

McMaster-Carr 6495K211, 6495K15, 6495K23, 6495K24

The one I used is 6495K211. 1:1 would not be a good choice with your motor. I recommend using a smaller pulley on your motor.

[MikeAber]

Speedre,

I weighed the spindle with the motor and the dovetail mount including the drawbar it weighs 20.2 pounds. Without the drawbar it weighs 19.8 pounds. Considering the motor alone weighs 10 pounds I guess it's a lightweight. I also fired up the 214 ozin steppers and there was no problem with my Z axis lifting and lowering the spindle at 60 IPM (my normal rapid rate).

Mike

[SPEEDRE]

Mike, I've got a K2cnc , 25" x 14" x 3" . If your Z will take all that I guess it's a moot question. I'm having the mini head cut tomorrow and the nut taken off, I don't have a spanner so I'll have done while it's at the shop . Next pulleys. I think I'll wait 'till I've built the offset adapter plate before I measure for a belt, or should I buy a belt and then make the plate? A belt is measured from a point on one then all the way around 'till you reach that point again correct ?. Sort of measuring the circumference.

[MikeAber]

Hi Speedre,

That's right, measure the distance around the two pulleys. I didn't order my belt until I had the assembly put together and made the measurement. The belts come in 1" increments so I provided a little over 1/2" (5/8") adjustment in my motor mount to adjust the belt. My spindle nut came off easy after I loosened the set screw and turned it clockwise to remove it.

Make sure when you cut the housing off that the finished size of the housing is at least 3.5" deep.

My drive belt should be waiting for me when I get home. I'll take some pictures and maybe a video of some test runs on the machine tonight.

Mike

[MikeAber]

Well, I received the 15" timing belt I ordered and it was too big!

Not to be disappointed, I warmed up my Industrial Hobbies Big Mill and reworked the motor mount to use the belt. I also ordered the other two smaller sized belts 12.4" and 13.5" from MSC. The pulleys have large flanges that were causing lots of problems for me so I cut them down to the size of the pulley with the belt installed plus 1/8" or so. Removed all the sharp edges, polished and re-blued the pulleys.

I installed the belt, nice and tight and fired up the spindle -- holy smokes, what a racket! -- cling, ching, tang, bang, clikata, tickata, clunkata, tuckata -- HIT THE E-STOP! -- the spindle nut spins off the spindle (left hand thread) and takes off into the stratosphere! Find the spindle nut, re-install it and tighten the nut to preload the bearings 200 or so pounds (mid range) and fire up the spindle again - this time slowly - clunk, clunk, clunk, clunk, clunk - something is wrong. Fiddle around for 1/2 an hour and finally loosen the motor mount, start the spindle again and it runs smoothly - too much belt tension was causing the spindle drive sleeve to flop around.

Run the spindle up to 5000 rpm for 5 seconds or so, everything sounds good, then the motor starts to load down more and more and more --HIT THE E-STOP!--the spindle nut spins off the spindle (left hand thread) then takes off into the stratosphere! Find the spindle nut, go to re-install it and notice the spindle is too hot to touch re-install the spindle nut, adjust the bearing preload to light preload, tighten the setscrew to lock it in place and fire up the spindle again - slowly. Now things are sounding better; I ran the spindle up and down the range of 0 - 5000 rpm and the motor is not loading down as noticeably. There are noises coming from the motor at high rpm that, for the moment, I choose to ignore.

Time for some tests:
http://www.cnczone.com/gallery/showp.../1751/cat/9016
http://www.cnczone.com/gallery/showp.../1750/cat/9016

I measured spindle runout when I received the spindle from LittleMachineShop.com with the same collet and end mill with the same results. 0.0002” runout on the spindle R8 taper and 0.0005” runout with a 3/8” collet and 3/8” end mill. This is consistent with my two gear head milling machines.

Further tests indicate the following:
1. With ABEC1 stock bearings you should not push this spindle beyond 3,000 rpm as the heat buildup is excessive and will destroy the bearings.
2. Heavy bearing preload is a disaster for the bearings and not necessary for my class of machine. I must run as little preload as possible for the bearings to stay cool enough to survive at 3000 rpm.
3. I will replace the motor pulley with a 10 tooth pulley to improve torque at lower spindle rpm as the treadmill motor is not a high torque motor at low rpm.
4. I will purchase some ABEC5 bearings to test the feasibility of using this spindle at higher rpm.
5. In comparison to my two other spindles, this spindle is very rigid and can handle aluminum with ease.

I used a .250” 4 flute HSS end mill to mill in 6061 aluminum .100” deep .050” step circular pockets with 50% stepover in .5”, .75”, 1”, 1.25” and 1.5” sizes at 20 IPM and 3000 rpm. All the pockets measured spot on and the spindle handled the job easily. My other spindles can not accomplish this level of accuracy in aluminum.

My conclusion: this spindle has made my mini gantry mill into something more useful than a toy to play with. I am very gratified.

Mike

[SPEEDRE]

Fabulous Mike. This is what I was hoping for. Great T.I.R. . Well I was put on hold for a few days at the shop. I'm having an old friend do it and he's got some rush work to do. So in the meantime, I think I'll buy the pulleys and a motor. I've decide to get some horsepower, argh argh argh. ( Tim the Toolman grunts ) More Power!!!!

[MikeAber]

Motors, Motors, Motors

The UPS truck delivered the motors I ordered from Surplus Center while I was testing the new spindle and motor under power for the first time yesterday. I put the box aside for later. Today I opened the box and took a look. These are the motors:
1. http://www.surpluscenter.com/item.as...tname=electric
2. http://www.surpluscenter.com/item.as...tname=electric
3. http://www.surpluscenter.com/item.as...tname=electric
4. http://www.surpluscenter.com/item.as...tname=electric

In the first picture you see from right to left:
#1 1.25 hp 100 VDC 5100 rpm
#2 1.5 hp 110 VDC 5100 rpm
#3&4 2.5 hp 130 VDC 6750 rpm 1.5 hp continuous duty @ 95 VDC (4000 rpm)

I tested them all today and discovered something interesting. Basically they are all the same!
All the motors have the same gage wire in the windings, the same size brushes, bearings, housings, magnets, armatures, commutators and shaft sizes. Where they differ is in the method of holding the brushes and insulation. They also differ in placement of the bearings as the housing styles differ with the brush support method. The only reason they have different horsepower and rpm values is due to the voltage rating specified. I ran all 3 motors at 100 VDC and at 130 VDC and could not tell any difference in rpm or power. I swapped armatures with # 1 & 2 and they ran great, I even swapped armatures with the motors # 2 and 3 by accident and # 3 ran beautifully (even with the small bearing barely held in place by the housing).

The verdict! #4 wins due to the price alone, @ $19.95 you can’t loose. It also has the best insulation, the strongest mounting flange (steel vs. aluminum) and did not require any modifications to the housing to remove the mount (it’s bolted on). I plan to order 3 more of these motors for other uses around the shop. I originally did not consider this motor as the specifications indicated the housing was 4” diameter when it is actually 3.25” – the same as the others.

The sweetest running motor was #1 – all metal housing and brush support plate. I will keep this motor for a backup as I already made a motor mount that fits.

Remember the noises motor #2 was making at high speed – I discovered the brush housing is cracked and the brushes were arcing severely at high speed (bakelite brush housing).

The big problem now is my vise – I’ve been using a drill press 4” vise - this spindle has so much power, I can’t clamp material strong enough to keep the end mill from snatching the stock out of the vise!


Pictures: All of the motors disassembled – look for yourself. Drive belt and pulleys, motor mount for motors 1 & 2 front housings are identical.
Motor mount for motors 3 & 4. Steel front bearing support, wide opening for airflow.
New motor mounted on spindle. Doing some test runs. Side profile; this is why a 4” diameter motor wouldn’t work here.

My tests today with the “Golden” motor don’t indicate a need to reduce the motor pulley size. Smooooooth, quiet POWER all the way to 6750 rpm (no bearing preload).

Do I hear ABEC5 bearings?


Happy? You Bet!
Mike

[JFettig]

Mike, its looking good. One thing your gonna want to do is add a fan to your motor, they get quite hot after only like 20 minutes of use.

When you modified the housing on that motor(added a mounting plate) did you just take the base off of the motor and modify it there?


Jon

[SPEEDRE]

Jay, since I'm following Mike also, how would you add a fan to the motor?

[MikeAber]

Thanks for the input Jon,

I am planning to add a fan. I noticed the fan on the pictures of your mill you posted. Is that a 1 liter or 2 liter bottle? Is your fan working out ok? How about some details.

I disassembled the motor to have free access to the front bearing support flange and keep filings away from the magnets. No need to remove the armature from the housing; watch out for the - spring washer - it is designed to be used in one direction only (with the fingers pointing away from the bearing).

I know you understand the rest Jon, this part is for anyone else that wants to make one.

I machined a 3.505” square .5” thick spacer blank and bored a 1.69” hole in the center to match the outside diameter of the bearing support on the motor’s 7” flange bearing support plate. I oriented the flange to the spacer and drew an outline of the spacer on the flange with a sharpie. I cut the excess off the flange with a band saw, then drilled and tapped holes for (4) 10-24 shcs and mounted the flange to the spacer. I trimmed the excess off the flange and the spacer to finish size (3.5”) in the big mill with a 3/8” square tool bit under the spacer to keep the surfaces square to the table in the vise. Then the spacer is removed from the flange and bored to the outside diameter of the slots in the flange. Reassemble the flange to the spacer, drill mounting holes in your new motor mount, debur everything and reassemble the motor.

Although different in execution, this mounting idea was sparked by Jon’s mount on his mini mill with this HUGE, POWERFUL, well made, cheap motor.

This vise might be the answer to my vise problem. I wanted a new 6” vise for the big mill anyway.

Thanks Jon,

Mike

[JFettig]

I posted a picture of mine here:
http://www.cnczone.com/forums/showpo...5&postcount=83
you want to use a shroud to shroud the air down around and through the motor as much as possible. If you dont put a tac on the top of the motor you could get a fan and fit it to that shaft that sticks out.

I would have prefered to have my tac on the spindle rather than the motor and a fan for the shaft that sticks out the top, but I did it differently.

The fan I have on top puts out about 40cfm and it keeps it rather cool. The plate it is mounted to is a 3x3" plate with tapped 6-32 in the corners(same pattern as the fan) and standoffs, I milled away part for air to get by. In the top of the motor theres 2 holes that I tapped 6-32 also to hold that plate down.

Jon

[MikeAber]

Wow! Were you reading my mind Jon?

I think you posted the reply before I sent the question.

Do you have a tach mounted? I plan to add the digispeed controll board to control spindle speed and a switch to switch between local speed control and controller speed control.

I'm working on a layout for the KBIC125 controller right now with TurboCadCam.

Thanks Jon,

Mike