LM Rail

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Originally Posted by GTJim

Well I've got THK blocks and assumed that I would need thier rails, but if thats not the case all the better.

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Unfortunately not - each manufacturer's blocks will only work with their own rails. I meant that the hole layout and external dimensions are generally compatible.

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Originally Posted by Jonathan

Price for the blocks is about normal:

http://www.wmh-trans.co.uk/Products/..._BLOCK_SIZE_25

At the same place 1m of rail is £65+vat. Where did you get those prices?

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I am getting mine from East Europe just like other components that are cheaper, some of them are about 50% of a price of UK suppliers.

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Originally Posted by vigen20

I am getting mine from East Europe just like other components that are cheaper, some of them are about 50% of a price of UK suppliers.

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Hi vigen, where about do you get your THK rail from. As I was looking for a pair of LM rails approx 1500mm long suitable for SHS25 bearing blocks and similar length pair of rails suitable for SHS20 bearing blocks.
Jim

Hi GTJim

http://stores.ebay.co.uk/FA-SYSTEM_L...34Q2ec0Q2em322

As posted in another thread a while back I've bought a couple of used profile rail and bearing sets from the above link. Been happy with the service and component quality. These are all used, hence the fairly reasonable prices.

If you are patient on ebay you may find cheaper, but if you want to get on with it then have a look through their store.

Thanks

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Originally Posted by chip

ive took a chance and bought some used rail off him sr15 for my y and z,just need the right lengths for my x axis to come up and im on my way..

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Should have waited and bid on it...his prices are OK but you'll do much better by bidding, unless you're really tight for time. What length rail did you get for Z?

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Originally Posted by chip

yes i should have waited,too impatient ,im not even sure it will be up to the job, i bought a little over 400mm for the z and about 1200mm for the y with the mind to cutting it down if need be as i still cant committ to a size of machine or design.

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Don't cut it - use the extra length to space the bearings out further. Normally the force on each bearing is inversely proportional to the spacing, so you want to space them out as far as you can (within reason, assuming what they're mounted on is stiff) to reduce the load on each and thus reduce the deflection. I got two 1150mm (hiwin HGH15) rails for my Y-axis, which is only 760mm travel but I wont be cutting the rails.

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Originally Posted by chip

ive only managed to find 1 working machine using it on his z and y axis,great little machine but he has 4 lengths of sr15 on his y axis alone.

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He's probably used 4 as unlike most of the good rails the SR series does not have an equal load rating in all 4 directions - http://www.thk.ru/cataloguespdf/sr-300e_cc.pdf ... but since you've already bought them I wouldn't worry about it - any profile rail is going to be a huge amount more rigid than the SBR20 rails you currently use.

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Originally Posted by chip

thanks jon
just got to source some 20mm rail for the x then i can crack on.

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What length do you need for X? I wouldn't worry about finding 20mm for your size machine and what you're cutting, 15mm will still be fine. You would get marginally better stiffness with larger rails, but I'd put money on other aspects of the machine contributing a greater error than the difference between 15mm and 20mm rails. There's no significant disadvantage to using bigger rails though, so if you do find some cheap then why not...

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Originally Posted by chip

i was just looking at the korean chaps shop,i didnt get the option to bid or make offers,he must have knocked that on the head.

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I meant just search on eBay (worldwide) in general. Rails long enough for Z and Y come up quite regularly, but you might struggle for X.