[chas]

Not completely sure how a typical thrust bearing
assembly would look like. Does anyone have a
cad drawing to enlighten me.
Thanks

[High Seas]

Maybe this helps - a quick rip from Mcmaster's catalog (more at: www.mcmaster.com)
Cheers - Jim

[sendkeys]

[ger21]

Are you talking about for a leadscrew? Check out these: http://www.nookind.com/endmount/EndMountsFlange.cfm

or here for a home made version: http://www.5bears.com/cnc04.htm

[chas]

So to ask a stupid question, they go between the end of the leadscrew(stepped edge)
and the bearing, opposite end from the step motor?

[sendkeys]

well thrust bearings goes


screw-thrust-bracket-thrust-washer-nut-coupler to servo/stepper


and frist thrust is smashes in the middle of the screw edge and bracket

the bracket is just little bigger then the screw so it can turn free or maybe use a smaller normal bearing(cheaposkate bearing ect) in the middle of the two thrusts and tight on the bracket. this would give you more up/down support. just make sure it doesnt touch side to side only up/down. Like use .3 inch thick bearing and .4 inch bracket ect

then last thrust is smashes on the bracket and washer/nut




i bet in the end this will cost you more then angular contact bearing.
like on the two above websites.

http://www.bearingsdirect.com/cgi-bi...art.cgi?CAT=55

[ger21]

You can make a bearing block like I linked to above using rollerblade bearings, instead of angular contact (which cost a fortune). They won't last as long as angular contact, but they are a fraction of the price and can easily be replaced when worn. And for small routers, they should still last quite a while.

[sendkeys]

http://www.vxb.com/miva/merchant.mv?...NGULAR_CONTACT

""Ball Bearings 17x40x10
Single Row Angular Contact
Axel Bearings
Lot of 10 Bearings ""

for 19.99 cheapest i seen center hole might be to big but for that price you can turn some smaller centers for it hehe

[Patrick2by4]

I guess these would be called angular contact bearings

[HuFlungDung]

Those be tapered roller bearings. Nothing wrong with using those on a low speed app. The principle of having to preload the bearings in pairs, to achieve proper running performance, is the same thing as you'd have to do with real angular contact ball bearings. Angular contact bearings use balls, not rollers. The "angle" of an angular contact bearing is the imaginary line of contact of the ball through the inner and outer races. Its not radial contact, but a few degrees off each side of the radial contact point. There, is that enough to muddy the waters up good?

[Patrick2by4]

I will be using these bearings on my y-axis. It will be spinning about 600~800 max. Hopefully I won't have any problems.

[High Seas]

I'm confused? So let me review, what is the question:

So to ask a stupid question, they go between the end of the leadscrew(stepped edge) and the bearing, opposite end from the step motor?

ANSWER
First: Not a stupid question.
Second: Yes, they can go at the opposite end of the motor - and you'd probably want a bearing that works in both lineal (along the rod direction) to support the rod pushing against the end plate, and radial (around the rod) supporting the shaft as it rotates.
Third: The angular contact looks like a good alternative - and the other thrust bearings have their uses as offered - does that help any?
Forth: Personally, I'm looking at the lower cost filled nylon bearings for the far end of the rod, and just keep a few on hand and replace as needed. I like the 5bears approach too. Hadn't considered beadings at the motor end - so this has all given me something to think about. Thanks guys!
:cheers: Jim

[chas]

Forth: Personally, I'm looking at the lower cost filled nylon bearings for the far end of the rod, and just keep a few on hand and replace as needed

"lower cost filled nylon bearings" ???

[High Seas]

You didn't say what size shaft. I had some Acme threadded rod turned down to 1/4 inch - so this is the part # 6294K91 I'm ordering today from:
http://www.mcmaster.com/
They're pretty cheap and have good Pmax and Vmax. You'll find all the details - just wander thru their online catalog!
Cheers - JIm

[Mr.Chips]

Don't forget tapered roller bearings must have grease which means some type of seal on both sides to contain thelubricant and keep out foreign material.
Hager

[chas]

Do most people have their thrust bearing (or substitute "thrust like" bearing) on
the end by the stepper (or servo) or on the opposite end?

[sendkeys]

you have to put it on the side of the servo/steppers because with the heat/cooling of the screw it will expand and put pressure on the stepper/servo.
Main reason you cant put "thrust type" bearings on both sides

[ger21]

you have to put it on the side of the servo/steppers because with the heat/cooling of the screw it will expand and put pressure on the stepper/servo.
Main reason you cant put "thrust type" bearings on both sides

Sure you can. With thrust bearings on both ends, you can actually put the screw in tension, which will let you spin it faster before it starts whipping. Look at the Nook catalogs. They list 4 types (classes?) of bearing setups. The best is the double angular contact at BOTH ends.

[fyffe555]

To add to Ger's comments;

Bearings on rotating lead screws can provide three types forms of support; rotation, location and stiffness. Lack of support can lead to vibration, backlash or leadscrew movement, nut wear and motor damage.

Simple ball bearings (skate bearing etc.) allow the leadscrew to rotate about it's axis.

A Thrust bearing will locate the leadscrew axially, along it's axis against the thrust produced by the screw. Since a leadscrew produces thrust in both directions it's normal to have a thrust bearing working in each direction.

Simple Bearings provide the support and effective stiffness or resistance to whip of the screw. One bearing on one end is not stiff, one bearing at each end is better. One bearing at one end and two spaced apart at another is stiffer, two spaced bearings at either end is the stiffest. The Nook catalog has an excellent description and explaination of this.

Thrust bearings bearings aligned to produce tension on the screw will increase its effective stiffness and further reduce whip.

Ball bearings, angular contact bearings, roller bearings and taper bearings are all different with different purposes. Some mix rotational support with thrust support. Note that thrust bearings are usually manufactured to produce or resist the thrust in one direction only.

A simple ball bearing and roller bearings are not thrust bearings but can provide limited though not designed for thrust alignment at the cost of wear. An angular contact and a taper roller bearing can provide both simple and thrust support but they are directional.

So, the best solution for location and stiffness is two spaced points of simple support at each end and a thrust bearing at each end in opposition, to provide tension to the screw. This or lesser degrees of support can be achieved by a combination of simple, thrust or combination bearings depending upon what you have and how much support you want.

It is worth checking the spec's of your motors and calculate the force you're producing with them via the lead screw. Most motor bearings, especially steppers are not engineered to support the forces axial to the shaft that are possible to be produced with a leadscrew drive. You can damage motors turning leadscrews without some kind of thrust bearing arrangement both towards and away from the motor.

Finally, and to further complicate the deal, on longer screw's it's an idea to put simple bearings on the carrige, either side of the drive nut to reduce the effects of whip or wear on the nut. I've an old 36" HP Plotter with eight bearings on a 36" 1/4"dia leadscrew....

[sendkeys]

Sure you can. With thrust bearings on both ends, you can actually put the screw in tension, which will let you spin it faster before it starts whipping. Look at the Nook catalogs. They list 4 types (classes?) of bearing setups. The best is the double angular contact at BOTH ends.

I guess im wrong I was just going off Every post i seen everyone said to keep one side free.But if nook sells them that way, it must work