Lead screw question

[KingRandy]

Hello everybody, my team this year would like to use a lead screw to adjust our shooter angle. I was wondering if there are any other ways to set it up besides a coupler?

If any of you are using a lead screw where did you get your coupler?
We're using a 2.5" CIM with 8mm bore[/size]. Thanks for the replies

[Bruceb]

Are you looking to drive the lead screw directly off a CIM shaft?
That is going to move way FAST.
You might like to think of using some sort of reduction first.

[kevin.li.rit]

You can usually get the lead screw nut and connector from the same place you got the lead screw.

It actually might not be too fast, a screw with 16 threads per inch will only move at less than 5.5 inches per second on a direct driven CIM.

What kind of lead screw are you using?

[Dan.Tyler]

Depending on the thread of the lead screw, it may provide adequate reduction by itself.

I have built couplers. You would need a lathe. Turn down the end of the lead screw, and bore out a piece of barstock to fit over it on one end, and to fit over the CIM at the other. Drill/tap each for set screws.

Something to note: adding a shoulder onto the outer side of the coupler and combining with a thrust bearing is highly recommended, rather than allowing the CIM to carry the load internally.

[Dad1279]

Last time we used a leadscrew, we used a #25 sprocket on cim, and another on the leadscrew, coupled with a short chain. I believe we used a sprocket with a bore smaller than 8mm and drilled it out, 5/16" is very close to 8mm

If you really want to direct drive, andymary makes an 8mm hub:http://www.andymark.com/product-p/am-0320.htm

Or you could use a vex versaplanetary 1:1: http://blog.spectrum3847.org/2013/01...-mounting.html

[DELurker]

Originally Posted by Dan.Tyler

Depending on the thread of the lead screw, it may provide adequate reduction by itself.

I have built couplers. You would need a lathe. Turn down the end of the lead screw, and bore out a piece of barstock to fit over it on one end, and to fit over the CIM at the other. Drill/tap each for set screws.

Something to note: adding a shoulder onto the outer side of the coupler and combining with a thrust bearing is highly recommended, rather than allowing the CIM to carry the load internally.

Actually, there's an easier way. Last year (2013), 1370 used a lead screw to control their shooter angle. It was a motor (CIM?) on a bracket (made on a drill press) with two AndyMark couplers screwed together (8mm stock & 3/8) flange-to-flange with the 3/8" diameter lead screw in the end of the hub. We did mill a flat in the hub and drill & tap for a set screw in the 3/8" hub. However, the milling can be done with a file just as easily and the drill/tap can be dome on a drill press or *shudder* by hand.

AndyMark part numbers:
am-0320 (8mm keyed hub)
am-0134a (3/8" keyed hub)

We supported the "free" end of the lead screw with a 3/8" IGUS bearing and put a shaft collar on it so if had no way to slip out.

However, we did find that allowing the deck weight to rest in the middle of the lead screw for long periods of time put a bow into the lead screw which led to a funny little wobble when we turned the motor.

I'll see if I can find some pics or take some new ones by the end of Thursday night's meeting (school's closed today - no work in the shop tonight )

[Dan.Tyler]

To help prevent the bending and funny wobble, you can utilize a linear track/carriage to constrain the bending moments that make the lead screw buckle.

Easier is, of course, a relative term. It's easier for me to get access to a lathe and piece of barstock than it is to find two specific couplers.

For many (most) teams it is opposite, and in that case would recommend your method. It sounds like it is exactly what the OP asked for.

[JamesCH95]

On our robot last year our main climbing mechanism was driven via lead screw. We milled the end of the lead screw into a hex profile that fit inside of a Vex gear and drilled/tapped the end and put a bolt in it to retain it on a flanged hex bearing. Worked pretty well and supported the whole weight of our robot.

[DELurker]

Originally Posted by DELurker

I'll see if I can find some pics or take some new ones by the end of Thursday night's meeting (school's closed today - no work in the shop tonight )

OK, it took a little longer than anticipated (weather and such), but here are some pics...

[DELurker]

Originally Posted by DELurker

OK, it took a little longer than anticipated (weather and such), but here are some pics...

And some more... (darned 5 image limit)

[Oblarg]

Turn down the end of the lead screw, use a bearing to take the load, and use a spider coupler.

[Mr V]

We used a lead screw to adjust our shooter angle last season. We drove it with a BAG motor attached to a Versa Planetary with the 1/2" hex output. To connect that to the lead screw and allow for the angle change we used a 3/8" drive 1/2" swivel impact socket from Harbor Freight. We turned down the very end of the Versa output shaft so it fit into the round recess in the socket so the socket fit as far as possible over the shaft. To attach the socket to the lead screw we drilled and tapped the end of the lead screw and enlarged the retaining hole in the drive side of the socket.