Ballscrew & Linear Rail Kit - Any Good

[WoodKnot]

Hi gents

Thank you all for the input and did not expect the response to this thread.

You all talk in riddles to me - as i could talk if i started about my industry sector.

I am not sure if i will be using the end bits with the bearings in, as they might not seat within the aluminium profile?

I thought that's what the end plates are for? or am I getting that wrong?

Most kits that i have looked at spec the bearings separately, so naturally assumed that i would not need those brackets (as per the image posted earlier in the thread)

Hope that makes sense

WoodKnot

[m_c]

Hi gents

Thank you all for the input and did not expect the response to this thread.

You all talk in riddles to me - as i could talk if i started about my industry sector.

I am not sure if i will be using the end bits with the bearings in, as they might not seat within the aluminium profile?

I thought that's what the end plates are for? or am I getting that wrong?

Most kits that i have looked at spec the bearings separately, so naturally assumed that i would not need those brackets (as per the image posted earlier in the thread)

Hope that makes sense

WoodKnot

The machines you're looking at, are designed to be as cheap as possible to build, and will typically use a couple basic thrust bearings to control screw end float. To be blunt, it's a rubbish method, as thrust bearings are hard to adjust accurately in such a setup, and they provide little to retain the screw co-axially, so once it starts spinning fast, the screw/bearings will start rattling around in each other and the end plates.
The BK bearing blocks should use two angular contact (AC) bearings, which get preloaded (aka you can tighten the nuts up so the bearings are loaded, unlike the before mentioned thrust bearings which would just collapse), and provide co-axial retainment of the screw.

Personally, I'd redesign the machines you're looking at, to make use of BK and BF support bearings (BF is just a basic deep groove bearing to support the screw).
The reason the mentioned machines don't use them, is they add cost. They cost more than a couple basic thrust bearings, and you need additional mounting plates for them.

The issue with cheap BK blocks, is it could be a gamble as to what bearings are fitted, the quality of the bearings, and if they're actually fitted correctly.

[A_Camera]

Hi gents

I am not sure if i will be using the end bits with the bearings in, as they might not seat within the aluminium profile?

The 1605 BK/BF bearing holders fit exactly (but not perfectly) into the 45 mm gaps of 45x90 extrusions if you want to install them across in two T-nut tracks using 6 mm screws, but you must consider the ball nut because that will need some spacer or other solution, due to the fact that the HGR20 + HGH20 is 30mm high while the ball nut flange demands 45mm...



...or 50mm if it is turned 90° high from the bottom.



You can solve that in many ways, but it must be solved somehow. I think you will see that more clearly once you get the stuff. It's easier when you have something in front of you to look at than just CAD drawings or words.

[WoodKnot]

The 1605 BK/BF bearing holders fit exactly (but not perfectly) into the 45 mm gaps of 45x90 extrusions if you want to install them across in two T-nut tracks using 6 mm screws, but you must consider the ball nut because that will need some spacer or other solution, due to the fact that the HGR20 + HGH20 is 30mm high while the ball nut flange demands 45mm...



...or 50mm if it is turned 90° high from the bottom.



You can solve that in many ways, but it must be solved somehow. I think you will see that more clearly once you get the stuff. It's easier when you have something in front of you to look at than just CAD drawings or words.

Thanks A Camera

I had noticed that all the converted ones that i had viewed that they had to create some sort of spacer block, but yes, i was waiting for the arrival of the parts, i think holistically first, so then have to work backwards to get all the joined up bits to work.

So i see what i want to achieve and how the look is perceived in my minds eye, then have to work backwards to achieve what i am seeing.

My issue is that i don't work to plans and do everything 'off the cuff' sort of speak, which can be a bit problematic!

WoodKnot

[A_Camera]

Thanks A Camera

You're welcome.

I had noticed that all the converted ones that i had viewed that they had to create some sort of spacer block, but yes, i was waiting for the arrival of the parts, i think holistically first, so then have to work backwards to get all the joined up bits to work.

Yes, some sort of spacing or other solution is necessary. It is definitely easier to figure out a solution once you have them in front of you, especially if you are not used to read mechanical drawings, but also if you are open to changes and can divert from your own design.

So i see what i want to achieve and how the look is perceived in my minds eye, then have to work backwards to achieve what i am seeing.

My issue is that i don't work to plans and do everything 'off the cuff' sort of speak, which can be a bit problematic!

WoodKnot

I also don't spend hours and weeks in front of a computer to CAD a machine. I think that's a lot of wasted time, unless you want to reproduce and sell those things. Every new machine is a prototype. I make sketches using good old pencil and paper, but even those are free hand sketches, rarely use a ruler for drawing. It's enough for me to have the design sketched and the details in my head. Of course, this results in a few extra holes, but so what...

Anyway, I received this today:



So far so good. What's funny is that the kit included four carriages. I have no idea how they are thinking... 200mm rails and four of those means basically no movement at all or maximum 46mm. I knew this when I ordered, I only need one on each rail, but this was the best price, so now I have two spares. BTW, even this BK feels fine to me, and I still think it is best to leave it as it is and replace the bearings with AC once these are worn out, if they ever will before I die or stop using it.

[WoodKnot]

So far so good. What's funny is that the kit included four carriages. I have no idea how they are thinking... 200mm rails and four of those means basically no movement at all or maximum 46mm. I knew this when I ordered, I only need one on each rail, but this was the best price, so now I have two spares. BTW, even this BK feels fine to me, and I still think it is best to leave it as it is and replace the bearings with AC once these are worn out, if they ever will before I die or stop using it.

They suggest 250mm but went for the stock 300mm, I suppose better to have greater travel then less?

[A_Camera]

They suggest 250mm but went for the stock 300mm, I suppose better to have greater travel then less?

This is a kit with 250mm ballscrew and 200mm rails. I need about 80mm motion that's why I chose this kit.

[WoodKnot]

This is a kit with 250mm ballscrew and 200mm rails. I need about 80mm motion that's why I chose this kit.

I presume A Camera that you can just set the limit switches on the Z axis to reduce the amount of required travel anyway