New Improved DrJoesDrillShaft

FIRST General Forum
#1

Posted by Joe Johnson.   [PICTURE: SAME | NEW | HELP]

Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 12/2/2000 7:27 PM MST

Hi all.

I have often recommended that teams make a custom output shaft for the drill transmissions. Last year I posted a sketch of a shaft that served many folks well.

I have made an improved shaft with an improved sketch.

The shaft is better because it is easier to make (the old shaft was a ‘carry over’ design that I had always intended to improve but never found the time) and it is intended to couple to a 3/8 inch shaft via a rigid coupling made by Ruland and available from McMaster (page 891 part number 61005K32 ‘One-Piece Clamp-On Coupling Steel, Without Keyway, 3/8’ Bore, 7/8’ OD’). It is also in the Small Parts catalog (I think).

The sketch is better because it has tolerances! There is a bit of a problem with the sketch in that some of the hidden lines became solid and a leader line to a 4 mm hole gets a little lost in the shuffle. But… for all its warts, it is still readable if you know your way around prints.

This shaft has been tested in our local robotics league (Oakland County Competitive Robotics Asso.). The were made to print by a local shop from the sketch. They worked great for the 15 teams or so that used them.

Good luck to all.

Joe J.

#2

Posted by Jason Iannuzzi.

Engineer on team #11, Marauders, from Mt. Olive HS. and BASF, Rame Hart, CCM.

Posted on 12/4/2000 9:19 AM MST

In Reply to: New Improved DrJoesDrillShaft posted by Joe Johnson on 12/2/2000 7:27 PM MST:

When we were considering using your original part, we made a few modifications in the design. It looked almost exactly like your version 2.0.

This year we’re ditching the gear boxes altogether, custom all the way. Good riddance to those.

#3

Posted by Dodd Stacy.

Engineer on team #95, Lebanon Robotics Team, from Lebanon High School and CRREL/CREARE.

Posted on 12/4/2000 4:33 PM MST

In Reply to: New Improved DrJoesDrillShaft posted by Joe Johnson on 12/2/2000 7:27 PM MST:

We had multiple disasters in 1999 around failure of marginal shaft splices on the drill gearbox outputs (mea culpa). Great for character building and education in the supportive wonderfulness of the FIRST community, but really a bummer way to spend a competition, compared to watching the games and digging all the kids and 'bots.

In 2000, we made replacement shafts per Dr Joe’s drawing - thank you, Joe - slightly amended by reverse engineering of the originals (third decimal place, Joe!). Talk about a difference! Advice to any new teams from 4 year’s fumbling:

  1. Make shafts, long enough to mount a shaft bearing next to the final drive sprocket.

  2. Run the gearbox in Hi. Do your final stage of gear reduction between the shaft and the drive wheels. Mount the drive sprocket on a Trantorque. You can change the sprocket, and - running the box in Hi - it won’t slip.

  3. Limit your gearing to a 7-8 ft/sec speed if your strategy is for a fast game - the torque loads work well for the drive system, and your drivers can’t handle any faster anyway. (Yeah, yeah, I know) If you can develop enough traction to play a grunt pushing game w/o flunking the carpet destruction test, you’re own your own for all of the above.

My real reason for writing is to ask the community’s opinion on the following question: Is it within both the rules and the spirit if someone arranged to have a machine shop fabricate (with materials in the SPI catalog) shafts per Dr Joe’s drawing and make them available at cost to any and all teams? Teams could take a hit against their SPI budget for the material and pay the machine shop’s nominal charge. I think that’s what we have done in the past, just making it available to all, regardless of resources.

I’m not offering to do this, mind you. I’m just asking. This has been an incredible pain in the past, and I’m just interested in how we can help new teams focus on the main business and avoid the bs. So, what do you say?

Dodd

#4

Posted by Joe Johnson.   [PICTURE: SAME | NEW | HELP]

Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 12/4/2000 8:20 PM MST

In Reply to: Shaft Rules posted by Dodd Stacy on 12/4/2000 4:33 PM MST:

Dodd,

Due to a bad decision (that was mostly due to yours truly) with regard to our OCCRA robotic league, we had about a dozen robots driving in circles at our first OCCRA regional!

I quickly worked to cover my tracks! Basically, I had to have 32 of these drill shafts FAST. As a result, I had to find a source to make them quickly. I found a local source to make them for $75 each, not the cheapest I am sure but they were to print and on time (2 days from print to parts).

I suppose that I could set them up to do it all over again if enough teams want them.

As to whether it is ‘legal’ or not, I suppose that it IS legal if the material is from Small Parts.

Other thoughts?

Joe J.

#5

Posted by Dodd Stacy.

Engineer on team #95, Lebanon Robotics Team, from Lebanon High School and CRREL/CREARE.

Posted on 12/4/2000 9:59 PM MST

In Reply to: I have a source… posted by Joe Johnson on 12/4/2000 8:20 PM MST:

Joe,

Not that you haven’t done enough for the cause - and just won’t quit - but how about asking that shop to quote on 200 shafts and 500 shafts, by, say Jan 15? (Were they a CNC shop?) Using SPI spec material. And NO PINS. Teams can press out the pins from the flange of the planet carrier in the gearbox and press them into the flange of the new shaft. I don’t know if the $75 figure included the hand work of pin installation or just reflected the schedule crisis.

And I agree with you - I think it’s perfectly legal.

Dodd

:Basically, I had to have 32 of these drill shafts FAST. As a result, I had to find a source to make them quickly. I found a local source to make them for $75 each, not the cheapest I am sure but they were to print and on time (2 days from print to parts).

: I suppose that I could set them up to do it all over again if enough teams want them.

: As to whether it is ‘legal’ or not, I suppose that it IS legal if the material is from Small Parts.

#6

Posted by Joe Johnson.   [PICTURE: SAME | NEW | HELP]

Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 12/5/2000 7:32 AM MST

In Reply to: Re: I have a source… posted by Dodd Stacy on 12/4/2000 9:59 PM MST:

I will have the source look at higher volumes.

One problem will be that folks will all want them ASAP as soon as they want them.

I suppose that we could ask teams to sign up (i.e. send in a check) prior to and perhaps a few days into the FIRST build period. Once we have the orders, we could cut loose the shop. It still is a pretty messy problem to deal with.

Anybody have any thoughts on how to make the material handling issues easier? Perhaps we could request that teams fill out a standard priority mail shipper and send it to us with their check (maybe teams could send us the actual box with postage afixed and everything – I don’t know).

Input is welcome.

Joe J.

#7

Posted by Michael Betts.

Engineer on team #177, Bobcat Robotics, from South Windsor High School and International Fuel Cells.

Posted on 12/13/2000 9:46 AM MST

In Reply to: I will look into it… posted by Joe Johnson on 12/5/2000 7:32 AM MST:

: I will have the source look at higher volumes… Perhaps we could request that teams fill out a standard : priority mail shipper and send it to us with their check (maybe teams could send us the actual box with : postage afixed and everything – I don’t know)… : Joe J.

Dr. J,

I’m sure that we can do whatever makes your involvement easier. Did you get any HV quotes yet? Team 177 would also be interested in participating.

Mike

#8

Posted by Joe Johnson.   [PICTURE: SAME | NEW | HELP]

Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 12/13/2000 10:09 AM MST

In Reply to: Re: I will look into it… posted by Michael Betts on 12/13/2000 9:46 AM MST:

Hi all,

I got the quote. Here is my problem.

How do I handle the requests?

My source is really only interested in one single order not 100 small orders.

So… How do we work this?

Two issues have to be resolved:

#1 Is there enough interest to make this worth the bother?

#2 If there is enough interest, How do we make this as painless as possible for me?

As to #1:
E-mail me if you are interested. If a sufficient number respond, I we can proceed to step #2. By the way, will someone run this past FIRST and ask them if it is ‘officially’ legal and also if they would help to publicize it via an e-mail?

As to #2:
Assuming we pass #1, I propose that folks that are interested send me a personal check and a pre-filled out priority mail label AND appropriate postage. I would take orders up to say, Wed. after kickoff. At that time I would place one order. I would payoff the bill with the money sent me and see to it that the parts were mailed out as promptly as possible. I suppose that teams would have the shafts in hand by the second Saturday after the kickoff.

Any thoughts on this proposal?

Oh yeah, the quote: with an order of 200 pieces, the shafts should cost teams about $40 each.

Joe J.

#9

Posted by Jason Rukes.

Engineer on team #109, Arial Systems & Libertyville HS, from Libertyville High School and Arial Systems Corp & SEC Design.

Posted on 12/13/2000 2:46 PM MST

In Reply to: Got the quote… …now what… posted by Joe Johnson on 12/13/2000 10:09 AM MST:

Why not see if FIRST would consider throwing the shafts in the kit of parts? This would make the competition a little more like CDI and it would help the rookies to get rolling quicker.

Just a thought.

Jason

#10

Posted by Joe Johnson.   [PICTURE: SAME | NEW | HELP]

Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 12/13/2000 3:34 PM MST

In Reply to: Of course it’s late, but … posted by Jason Rukes on 12/13/2000 2:46 PM MST:

If I were king, it would be done! But as it is I remain a lowly serf.

The $40,000 that it would take to put a set of these beauties in every kit would be worth it in my opinion.

One thing that I believe would be possible with more advanced planning would be too make a powered metal tool to make the carrier part of the shaft and then to make a much simplier shafts that would press into the powdered metal carrier.

Basically the shafts could be made from 12mm drill rod (a stock item). All that would be required is a lathe to cut in 2 snap ring grooves to take thrust loads and a smaller diameter shoulder to with a knurled O.D. (e.g. 8 mm – leaving a 2 mm step that can be used to make sure the carrier is square to the shaft)

The 12mm shaft would require a different coupling (Ruland Part Number: MCLX-12-12-F). But this should not cause any particular difficulties for most teams.

I guess that the tool for the PM part would cost FIRST about $8K and then the parts would be essentially free (under $1). The shaft would cost about $5 each I suppose (in quantities above 100 or so, less if they went for a 1000 or more). The pins would be pretty cheap, let’s say $0.50 for all 4 (You can buy them from McMaster.com #91595A215 for $11/100 – no need to use the ones from the drill part if you are not going to held to FIRST material usage). Pressing in the shafts and the pins in would probably cost another buck in labor. Total bill: $11 per kit plus a one time tool bill of $8K. FIRST could make enough for 500 kits for $13.5K. The big savings comes the next year when they get enough for 700 kits (40% growth rate) for the low low price of $7.7K.

Bite the bullet. Buy the tool.

Joe J.

#11