May JR's legacy continue #4 - North Carolina, USA

[Robert M]

Woouawy wouwoaw…. Sexy stuff !!
CNC porn at it’s best !!
Sensational. I never doubted it would be amazing! You & Marcs work is very inspirational & motivating for me, It justifies the effort for me trying to do some rather than buy ready made !
Thanks for sharing all this
Robert

[Marc Shlaes]

Thanks everyone!

Now that we know they work, I'll post the DXFs. The drawings need a little cleaning. Sometime tomorrow probably.

[domino11]

Marc and JR.
Wow, looks really great. Can you tell us a little more on cutting the aluminum on the mechmate? Bits used, feed rates, difficulty of the cuts etc. I am sure a lot of fold are interested in the mechmate for some simple aluminum work as well as for wood.

[Marc Shlaes]

Heath,

JR and I will get together tomorrow and document the experience. I post the DXFs then. Just got done with all the things I had to do and that didn't leave much time for the things I want to do.

[Alan_c]

J.R. / Marc

Very nice work, just one question - would it not be better to rotate the whole belt assembly on the motor mounting plate so the motor is on the opposite side to the spring, that way the spring would have less work to do and gravity would help to keep the pinion engaged. Thats an awfully big lump of steel way off to the side adding extra load on the spring.

[Hugo Carradini]

Hello guys. I definitely feel honored to belong to these forum. I don't say much, but cant be away from the forum more then two days because I get anxious. There is so much good information that the teaching never ends. Congratulations and hope Gerald will be proud off the good friends his making and the nice technical level they are showing.
Saludos a todos

[domino11]

Marc and JR.
Since we are waiting for your post tonight on more info on your wonderful transmissions, I was thinking, is 3:1 the most gearing you can get in the size you have? Or is a slightly larger reduction possible? Say 7.2:1 like the geared oriental motors.?

[smreish]

that 7.2 would be hard to achieve. That's a pretty big toothed gear and I don't see anything in my browning book or sterling drive products (SPD) that has anything really over 60T that is a "stock" item.

Sean

[Marc Shlaes]

Thanks Sean. I believe that you gave the correct answer. However, to my eye, and I am certainly no expert, 3:1 or maybe 4:1 certainly seems adequate.

JR and I, regrettably, didn't get our joint "designing and building the transmissions" post completed before we both had to go off and do other things. Very Sorry. We will get it done tomorrow! Promise!

Marc

[cobra427mnsi]

I only have the table,gantry and carriage built at this time so I know nothing of cutting quality, speeds, gears, motors, etc. So this may sound silly, but could you use the geared motor (7.2) with the transmission to achieve a (3X7.2) 21.6 ratio or the 3.6 geared motor to achieve a (3.6X3)10.8 ratio . I don't know if there would be any advantage or disadvantage to this idea. Its just a thought.

Paul

[smreish]

Paul,
You could do that...but it would be cost prohibitive. Oriental sells the geared motor package up to 36:1 ratio's. If you need higher than that, then I would look at servo and real worm gearbox's instead. Of course, now were talking about a machine that is the next class up from the Multicam, Mechmate, Shopbot, etc.

My 2 cents.
Sean

- I'm allowed today ,it's my birthday!

[Marc Shlaes]

Sean,

Happy Birthday

[Marc Shlaes]

All right... Here is the info, We still have some work to do on the DXFs. Mostly documentation because the features mean something to us but maybe not to everyone without more doc.

Why? Frequently during plunging operations, the direct drive motor on the Z axis would lose steps. To avoid that, these operations were slowed considerably.
Occasionally, when jogging at high speed, the X axis would also lose steps. This never actually occurred during a cutting operation but because of earlier experience jogging, always had the feeling it might.
Also, felt that the increased resolution would help cutting accuracy.

Result: Resounding success. There is more power than needed, more speed and increased accuracy. More speed sounds counter-intuitive. Slow the pinion down by a factor of three and things speed up??? There is a trade-off between speed and torque. The previous direct-drive situation basically didn’t have enough torque to maintain a higher speed. Once the torque was increased, One could “dial-up” the speed in Mach and still be well within the power curve of the motors.

Design: We designed these transmissions in such a way that they would bolt right onto the existing motor mounts for the “Classic” as well as the “Mamba” and not interfere with any other components on the machine. This desire limits the gearing to about a 4:1 maximum advantage. If you want to replace the MechMate motor mount in a different design, you could achieve a higher ratio. But, again, that wasn’t our desire.

Fabrication: First a disclaimer… We are not machinists and therefore the speeds and feeds were decided upon via trial and error. If you know more about the process of machining aluminum with a 10,000 RPM router, please add your thoughts into the thread on Speeds, Feeds, Bits and Materials. With that said, here are the parameters we used.
Bit – Primarily a 1/4in. up-cut carbide WOOD bit. Don’t yet have any of those fancy end-mills (my address is… ) For holes, we used a real drill bit. The router spins way faster than a drill but it wasn't a big problem. The router bit just tended to make a blob of molten aluminum on a straight down plunge.

Note: measurement units are “inches”.

Speeds and Feeds: Feed Rate 20ipm, Ramp Angle 15 degrees, Ramp Feed 10ipm. For spiral pocket operations, we used a 30% Step over. Maximum cut depth per pass was .063.
Critical areas such as the press-fit bearing pockets received 2 full-depth-of-cut finish passes of .010 each.

Coolant / Lubrication: The following were all tried. None, some, compressed air, WD-40, a solution of naptha and Marvel Mystery Oil (available in auto-parts stores) in a 90:10 mix. This actually worked the best. This mix was typically applied with a 1in. natural bristle paint brush. Make sure you get a looooong handle and stay out of the way!!!!!!!!!!!!!!!!.

SDP/SI part numbers:
Drive Pulley: A 6A 3-15DF03716 4 $9.84/Each $39.36/Total
Driven Pulley: A 6A 3-45NF03716 4 $17.42/Each $69.68/Total
Belt: A 6R 3-054037 5 $4.73/Each $23.65/Total (Bought an extra belt)

The driven shafts were fabricated out of .5 in. x 3.5 in. cold rolled steel rod.

Bearings: 1.125 OD x .5 ID x .375 (Part:1616ZZ) sealed ball bearings from VXB (KIT 958) Qty 10 $24.95

Aluminum Stock: Cast Tool and Jig Plate. .5 inch bar stock would also probably work for less money. Just don’t know how dimensionally accurate it would be from your supplier. If in doubt, jig plate is very accurate.

[Robert M]

Marc, JR,

Thank you Sooooo much for sharing this valuable information.
this will help many ones, I’m so inspired by this that I’m planning to do those !
Hopping one day I too can come to your help & obviously to others too !
Amicalement, Robert

[Doug_Ford]

Happy birthday Sean!!!

[grandpi]

Happy birthday Sean!!!

Marc,

Is it possible to place an order to buy you directly 4 belt drive transmission, ready made. I would like to know too if my motors shaft lenght was enought long : 37mm.

Bye,

Pierre.

[Marc Shlaes]

Pierre,

Let me check all the parameters of the motors. If they are NEMA 34 and they appear to be, everything should work just fine. I'll let you know today.

[Alan_c]

Marc & J.R

I asked this the other day, but maybe you missed it in the other discussions:

Very nice work, just one question - would it not be better to rotate the whole belt assembly on the motor mounting plate so the motor is on the opposite side to the spring, that way the spring would have less work to do and gravity would help to keep the pinion engaged. Thats an awfully big lump of steel way off to the side adding extra load on the spring.

any comment?

[Marc Shlaes]

Alan,

Sorry...

It does seem that you might be right but, we thought about it and discussed it some and actually didn't feel that it made any real difference. That spring is pretty strong. Just our thoughts.

Are you using direct drive or geared motors. If direct drive --- it is a great improvement.

[domino11]

Marc, JR,
Do you think your belt drive solution would be a better cost/perfrormace point than the geared OMs? With this setup you could also go to the PK299 series motors that have more torque? If I remember right, Mike Richards had a preference to the PK299-F4.5 as being one of the best motors he has run? But they dont come with a gearhead option. So maybe your solution would allow us to use those? What do you think?

[J.R. Hatcher]

Heath thanks for the mailer.
I'm using PK 299 01A. I would rather have PK 299-4.5 because of the voltage difference.
As for cost and value of the transmissions (time and money), right now my brain can only think about how much time it took to develop the things. I need to cut several sets and forget about development to get the real feeling of value. I am convinced by the performance of the MechMate that they are a necessity over direct drive motors.

[Alan_c]

Thanks Marc

Currently I have a direct drive set up (PK299 F4.5A) so am very interested in your development as I will most certainly want to make a set myself - distances between us are too great for me to source them from you.

[Marc Shlaes]

Alan,

No problem. I'll get the DXFs there so you can see how we did it and modify to your needs and local availability (i.e. Metric pulleys and belts)

[J.R. Hatcher]

There was a concern about the orientation of my trannys. I setup and tested the difference between the 2 options.

1. With the motor farthest from the pivot point, (like I have them in the pictures. Ref. post 329 this thread) the fishing scales read 4 lbs.

2. When rotated 180 degrees the scales read 2 lbs.

The tension spring pulls 26 lbs.

Conclusion: The spring is either putting 22 lbs or 24 lbs respectively of pull on the rack via the pinion.

My thinking is, the installer should orient the transmissions the way he thinks they look best or are just out of the way better because the other differences are not that impressive. IMHO

[J.R. Hatcher]

This is a video cutting aluminum that I uploaded to You-tube. I thought I had posted it here but can't seem to find it, so here it is..... maybe again .

http://www.youtube.com/watch?v=TBJoNwArX9U

[J.R. Hatcher]

I just tried the link and it did not work until I clicked on.... watch in high quality then it started to play instantly ???????????

[domino11]

JR,
I had no problems with your link.

[grandpi]

Hello guys,

Just would like to know where i could find the dxf reduction belt files and/or waiting for a quick quote to buy them readymade to N.C.I.A.M.T.S.F.
.
Keep in touch ...

Pierre.

[J.R. Hatcher]

Just a few thoughts this Saturday.

Marc and I (back before Sept 24) had plans to sell some laser part kits. So in an effort to make it as painless as possible we made some changes in the DXF cut files. We included a file for the Z plate with all the holes laser cut, even the ones that were getting threaded. We rearranged some of the holes to miss our router brackets since we knew exactly where they would go. We then used hex head bolts, cheap and easy to attain (no need to countersink [fast]). We added 2 holes for the gas spring bracket. Now that we knew the Z plate width, we had the right holes cut in the spider plate, even the one for the gas spring. The motor mount plates got all holes cut, when I threaded them they came out perfect, no problems at all.
Other changes made.
1. Increased the length of the gantry tubes by about 3/8" to make room for full depth nuts between guide rollers and stiffeners. This in turn kept me from having to countersink the holes for the motor mount swing bolt, was able to use a hex bolt and easily get a wrench to hold it (no need to slot the end of the bolt)

One other thing I did that saved a lot of time was just hand held the side grinder and removed about 75% of the material from the 45 degree cuts on the rails then use the skate (careful very easy to screw up a rail). You'll have to use very large nuts to do this.

These changes saved a lot of time, without taking anything away. JMHO

I also made a change to the new skate, 2 very small rollers ride the rails now (easy to adjust).

On my next MM I will extend the rails 1" or 2" past the ends of the beams to put guards for the rollers w/ tubes that hold spring loaded oiled felt to ride and clean the rails.

If you want I'll send other ideas or changes we made as I remember them?

If you try um you might like um.

[Gerald D]

Ah, the voice of experience! Looking forward to lots more pics . . .

Well, you didn't expect me to keep my big mouth shut, so here goes:

- The z-slide drawings show a precision, high-strength steel. That is something that the laser cutting companies do not generally keep in stock. Also, I doubt they would cut the holes accurately in relation to the outside edges. They throw a big sheet on their tables and then cut all around the edges to get their accuracy. However, this may come as a surprise, that high-strength steel is as flexible as mild steel. A mild steel, laser cut slide will have the same stiffness, but the edges may wear out quicker where the rollers mate. Realise that the z-slide makes very short, repeated movements and wear resistance is a big factor in using that special high-strength steel. In summary, I am mainly afraid you might sacrifice wear resistance if you use typical laser cut steels.

- Hex head screws tighten better than countersunk head screws - the cone of the countersunk binds in the taper. However, one day when you might go to a typical Italian spindle, you will see it has a flat face which slaps against the z-slide - then you may wish you had countersunk in the first place.

- Any increase in the length of a gantry tube will slide the pinion gear further off the shaft of the motor/gearbox. Already my pinions are slightly off the end of the shafts because I have metric racks at 16mm wide. The geared motors also have slightly shorter shafts than the direct motors. I did all the exotic countersunks and half-nuts to get the pinions as far onto the shafts as possible.

- I have the nuts to rough freehand grind the rails first, but I don't have the nuts to let a staffer do it.

The rest of your points are also interesting - waiting for pics. Thanks