New Build of a Joe's CNC Hybrid R&P 8x4

Hi all,
My name is Graham and I'm in Boston Lincolnshire, I have been looking at building a cnc for quite a while now.
I have no experience at all at the electronics side of things- done cabinet making for 30 years.
With that in mind I decided to go for a set of plans by a chap called Joe in the USA.(Joescnc)
The machine itself is called a hybrid and I will be adding the upgrade of rack and pinion instead of ball screws.
The machine will be capable of cutting 8ft x 4ft boards although the original plans make a 4x4.
With Joe's plans- you purchase them and this gives you access to his builders forum where there are cutting files and various mods that people have included over time, also a few hundred build logs of all of these mods and plans put into practice.
I'm hoping after all these people have built and upgraded the machines that it might have most of the problems sorted out and so be fairly straightforward! lol
build log here
http://www.mycncuk.com/threads/11777...938#post100938

Hi Graham
Welcome to the forum
It all depends on your intended use of the machine but if you are intending to use it in anything resembling serious production you might want to have a rethink, best bet would have been to have a look @ some of the build logs here on the forum to get an indication what is actually required to produce a solid reliable machine. just had a quick look on youtube and not impressed with the machine.Don't be put off though the guys on the forum will point you in the right direction.Rule number one don't buy any kit until you have a design drawn up.best bet for now is read the build logs, there is a wealth of hard earned information on the site.
Good Luck
Regards
Mike

Hi Mike, thanks for the input :)
The machine won't be in use running all day, gonna be a learning curve /machine for me.
Hopefully it will upgrade itself over time, ie changing out the mdf carriage sections for plate Ali.
Maybe also upgrade to linear rails.
While I know it's not gonna be a high spec machine by any standard, it's a case of this or nothing to get me started.
I do have my base built already, hopefully I'll get some pictures up later and then be able to take on board some on the go advice :)
Cheers
Graham

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Originally Posted by GrahamWhite

The machine itself is called a hybrid and I will be adding the upgrade of rack and pinion instead of ball screws.

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R&P isn't an upgrade to ball screws it's very much going backward.!

However it is little easier on longer machine provided it's done correctly.

Now regards the machine then to be fair unless you got Plywood cheap then could have built a frame made of steel for about same or not much more. Obviously you'd need to be able to weld but steel isn't that expensive.

Also if your thinking to use the V bearing and Angle style setup for linear rails then please let me urge you to save up and buy some proper linear rails, even the round type if you must.
All your doing with V bearings is building trouble and wasting money because they will stick, wear and be inaccurate. You'll be for ever chasing issues.

Often people think they'll start off and upgrade as they go along just like your thinking but the reality is that rarely happens and even when it does still lacks in many ways because can't make silk purse out of sows ear.!
Also the costs of intial build plus any failures plus upgrades will work out more than doing it correctly first time.

You don't seem to far down the line with only base made so I'd urge you to maybe stand back and take look at what can be done in steel.
I know 100% you won't regret it if you did. Also know you will regret building joe's machine at some point.

Sorry to be negative but it's in your interest we say it.!

Cost for me is a major consideration I'm afraid.
I would rather have a machine that needs adjusting from time to time,than no machine at all.
I looked at ball screws after your comment (the original machine actually had lead screws not ball so my fault there) and while on short runs theyre fine - it is suggested for 3.0m that at least 25mm screws would be needed- at £300 each just for the screw that's a bit out of my budget!
I am seriously gonna consider going with square linear rail though - even if it's 15mm - £120 for 2 rails with 4 bearings@ 1500mm long each side and then double rail on the X axis as well.

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Originally Posted by GrahamWhite

Cost for me is a major consideration I'm afraid.
I would rather have a machine that needs adjusting from time to time,than no machine at all.
I looked at ball screws after your comment (the original machine actually had lead screws not ball so my fault there) and while on short runs theyre fine - it is suggested for 3.0m that at least 25mm screws would be needed- at £300 each just for the screw that's a bit out of my budget!

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R&P is good for a long machine provided done correctly but can't compare to ballscrews for accuracy or reliability/repeatability. Also requires much more upkeep and if not done correctly wears quickly and can be a pain with sticking etc.
Yes you would need 25mm screws that's true but don't let people tell you they are no good for long runs because that's simply not true. They just don't know how to do it correctly.
Also if bought from China they won't cost £300 each. Last long screws I bought cost $198 for 2 x 2850 25mm dia 25mm pitch. Obviously got shipping etc but if you buy in package with rails etc you will be very surprised at the price.
You will pay more for those CNC router parts R&P kits than you will for ball screws.

Quote:

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Originally Posted by GrahamWhite

I am seriously gonna consider going with square linear rail though - even if it's 15mm - £120 for 2 rails with 4 bearings@ 1500mm long each side and then double rail on the X axis as well.

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Again check out China you'll probably get 20mm for same or less money. Also While it's possible I Wouldn't join the rails, difficult to get clean join and if not done correctly you'll get premature wear of bearings. Also no need because can get 3000mtr lengths.

Go to this site and email Fed Lee asking for quote. Mention Dean from Uk sent you and you might get a pleasant surprise.!

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Originally Posted by JAZZCNC

Go to this site and email Fed Lee asking for quote. Mention Dean from Uk sent you and you might get a pleasant surprise.!

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Sorry I don't see a link or a name for a site ?

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Originally Posted by GrahamWhite

Sorry I don't see a link or a name for a site ?

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Opp's here you go. https://bstmotion.aliexpress.com/store/314742