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Turning a system by 90º part 2
2

Turning a system by 90º part 2

RE: Turning a system by 90º part 2

thx, it's nice to see the final result.

another day in paradise, or is paradise one day closer ?

RE: Turning a system by 90º part 2

Nice looking piece of equipment.

RE: Turning a system by 90º part 2

(OP)
hehe, yes

We could have taken the net out for the picture

I wanted to have more vivid colours, but the options were very limited


RE: Turning a system by 90º part 2

That looks sharp!

RE: Turning a system by 90º part 2

is the CG of the thing on this tool close to the rotation axis ?

another day in paradise, or is paradise one day closer ?

RE: Turning a system by 90º part 2

(OP)
Yes; The idea is that the center of gravity is in the axis line

There are many cables, components, screws... so it is not easy to know. Below the blue plate one can see a black thin one. We have different thinknesses (of the black plates) to play with the distance

cheers,

RE: Turning a system by 90º part 2

I think this is a case of "near enough, good enough". The guy on the hand wheel will know where it is !

another day in paradise, or is paradise one day closer ?

RE: Turning a system by 90º part 2

... but probably too late !!

RE: Turning a system by 90º part 2

(OP)
Back to this project

I'm afraid the two shafts might not be well aligned.

How to position the block bearings so their axes are coincident?

We have cut an aluminium L-profile to connect the shafts (the inner ends have a square section); but this doesn't not guaranty anything.

The bearings have a spherical outer surface to compensate for misalignment.

We have a self-leveling cross-line Laser (Bosch GLL 3-80 CG), so we could see from the side and top the laser on the shafts, but the lines are two thick.

What can we do to align the shafts/bearings?

How is this done normally (I mean having two bearings with a shaft is a very standard setup)?

thanks

RE: Turning a system by 90º part 2

Lining the bearings with the laser level should be fine for this.

Spherical bearings and low speed. You don't need very precise alignment.

RE: Turning a system by 90º part 2

(OP)
The speed is not a problem, but the torque

If the shafts are not aligned there will be additional forces

It seems also difficult to place the gearbox in its position: it's heavy. It can easily tilt the shaft

Here some pictures





RE: Turning a system by 90º part 2

The diagonal braces under the gearbox are useless the way they are now.

RE: Turning a system by 90º part 2

As clearly stated bi rb1957 it is important to know where the center of gravity is located : if it is not in line with the shaft (that is the center of rotation) it can be a problem.
I know it is a bit off topic but it can be a suggestion for the future and different applications. The position of C.G. is always plumb (concrete flume) and always inside the footing base (pipe. Furthermore in such a case it is not needed even to anchor the base to the ground)

RE: Turning a system by 90º part 2

@MintJulip

Are you referring to the diagonal braces carrying the load down the stretcher section of the frame? If so, I agree. I think the weight of gearbox could induce some twisting of the stretcher which could lead to difficulty in aligning the gearbox and the shafts even if it is a "3030" type extrusion. It might not be as clean, but a pair of vertical legs going down to the floor with adjustable leveling feet could support the gearbox directly.

I can't quite tell from the photos but is the turning assembly on casters?

Kyle

RE: Turning a system by 90º part 2

I don't think the spherical bearing mounted next to the gearbox is of any use. I'm guessing the output shaft of the gearbox is rigidly mounted. Unless that spherical bearing is concentric to the gearbox shaft you might have large radial loads on the gearbox bearings.

RE: Turning a system by 90º part 2

(OP)
This structure below the gearbox (made out of aluminium profiles) is to relieve the shaft from the gearbox weight.

Since the bearing has this rotating feature if the axis of the gearbox is not well aligned with the axis of the shaft it will tilt it.

We could add some screws under the gearbox to place it in its theoretical position

The question is how to align them properly? How can one measure the position of both axes?

Here another side picture

The assembly turns on the two bearings. And the center of gravity is on the axis of the system. The difficulty is aligning the axes of both bearings and the gearbox

RE: Turning a system by 90º part 2

Quote (Me)

The diagonal braces under the gearbox are useless the way they are now.

Quote (BrianE22)

I don't think the spherical bearing mounted next to the gearbox is of any use.

RE: Turning a system by 90º part 2

Hi drodrig

Well my first observation is that there appears to be no shims under any of the bearing mounts or gearbox, my company made steel rolling mills which had numerous fabricated frames with rollers mounted between two bearings and driven by geared motors so it was a similar set up. We always had shims to adjust the height of bearing housings and geared motors because you can’t achieve perfect alignment unless the tolerances on the machined components were so tight that it made it uneconomical to produce. In addition to the shims and where possible we built the frames up and had bearing housing pockets machined on both sides of the frame simultaneously to ensure horizontal alignment and used the shims for vertical alignment, also we used laser alignment tools and shimmed accordingly. What tolerances are specified on the component drawings that you are making this thing from?

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

RE: Turning a system by 90º part 2

Quote (desertfox)

We always had shims to adjust the height of bearing housings and geared motors

I don't know what shims are, but OP uses aluminum extrusions, meaning the height of the gearbox can be easily adjusted, i.e. exactly aligned with the shaft.
You mount the shaft, you mount the gearbox on a shaft, and then you just put the structure underneath the gearbox. You let the shaft and gearbox dictate where the supporting structure will be, not the other way around.

RE: Turning a system by 90º part 2

(OP)
The vertical alignment is not a problem because we have the aluminum profiles that were cut at the same length. We can adjust the whole supporting frame (4 feet at the ground).

The problem is the horizontal alignment.

desertfox, you wrote:
we built the frames up and had bearing housing pockets machined on both sides of the frame simultaneously to ensure horizontal alignment
Could you elaborate more that? do you have some pictures or sketches?

Scuka,
I understand shims are parts to move up or down the bearing (like a wedge, or screws)
Your assembly procedure seems logical. But the gearbox is heavy and it is not easy to inset the shaft into the gearbox hole (we need to use clamps). Since the bearing block can rotate it is not easy to align the first shaft

RE: Turning a system by 90º part 2

If you had spherical bearings that were allowed to work on both ends you'd be o.k. with some misalignment. Problem is that the spherical bearing located next to the rigidly mounted gearbox output shaft isn't able to wobble. If you have slop in the output shaft it may be able to move a bit but that's really not the way to go.

RE: Turning a system by 90º part 2

^ that's a good point.

Bearings compensate for angular misalignment, but if they're not at 0° (which they never are, that's why these bearings are used in the first place), the end of the shaft wobbles. If there's a gearbox, it constrains the wobble, which might create problematic forces one didn't expect.

RE: Turning a system by 90º part 2

Hi drodrig

See sketch, I have a 'I' beam right hand and left hand frame joined by an 'I' beam running horizontally across, plates are also welded to the top of the'I' beam and the whole thing is mounted in a machine and the welded plates on top of the 'I' beams are machined across in one go to ensure horizontal alignment.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

RE: Turning a system by 90º part 2

I'm not sure a machined frame would help - pillow block bearings use over-sized clearance holes for the 2 mounting bolts. You'd still have a problem in the horizontal plane.

RE: Turning a system by 90º part 2

I'd modify the blue bracket next to the gearbox to accommodate a spherical bearing inside it and get rid of the pillow block support on that end. Then maybe something like a "lathe dog" to transfer the torque to the bracket.

Or use a flange mount pillow block mounted to the left blue bracket (with a lathe dog):

https://www.mcmaster.com/pillow-blocks/mounted-bal...

RE: Turning a system by 90º part 2


We also used to machine the ends of the pillow block and make a machined fit with the pocket in the frame, so a tight clearance fit, the hole being oversized wouldn't matter then.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

RE: Turning a system by 90º part 2

(OP)
The bearing in the Two-Bolt Flange looks very nice. Easy to align.

What about making a long bar (1450mm - 4.75 feet) sticking it in the gearbox and then position the bearings. Even with the block bearings

I have to check with our workshop if they able to produce such accurate rod. Maybe using different sections connected by dowel pins

RE: Turning a system by 90º part 2

I think a long shaft would work well for your application. There will be slop in the 3 shaft/bore interfaces and deflection of the bar. Those you can calculate to make sure alignment error is within acceptable limits.

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