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  1. #1
    Ok, on the advice of Jazz, I've decided to start a Build-Log. And those of you old enough will know why I've called it BIG RAT

    Anyway, I hadn't really thought of doing this as construction of anything still seems a long way off, but as Jazz said a BL is a good way of keeping all related content and stupid questions together, 'stupid' is my addition, not jazz's ;-)

    Like most people, I've been lurking for quite a while and whilst I feel I'm starting to get an idea of what I want, it seems that my path diverges upon the turn of every corner and I'm left feeling overwhelmed at the complexity of making so many decisions.

    I've been following AndyUK's build log with extreme interest and that seems to be the sort of machine I would be happy to end up with. Ideally, I'd like a machine that has a cutting capacity of 1.2m X 0.8m but I'm also looking at the possibility of using it for Aluminium (I'd like to be able to use it to machine any parts and plates for future machines/upgrades) but I'm worried that in trying to make the machine at this particular size, that I'll end up compromising things and that it will do neither well unless I throw a lot of money at it. Whilst money is not too much of an issue, if I can keep the overall spend under £2k that would be good. More than that and it'll start to eat into my other interests.

    So, off we go

    For a floor standing machine, what sort of height should I be aiming for the main supporting frame/structure. i.e how far from the floor do most people make the actual bed of their machines?

    Now I know that no 2 of us are built the same and what's suitable for someone who's 6'6" won't be approprite for Peter Dinklage, but I'm a pretty average 5'10" so what would be a good height to choose? What heights do those of you who are around that height use, and use comfortably?

    Cheers

  2. #2
    Quote Originally Posted by joe.ninety View Post
    I've been following AndyUK's build log
    Aww thanks. Definitely read through Joe Harris' build log. I based mine on his machine. His is better! More detailed log with videos on youtube and everything.

    Quote Originally Posted by joe.ninety View Post
    I'd like a machine that has a cutting capacity of 1.2m X 0.8m
    Don't forget to factor in footprint size vs cutting size. My footprint is 1.2x1.0, I can cut about 0.90x0.65, but I haven't exactly tailored to maximum build size.

    Quote Originally Posted by joe.ninety View Post
    Whilst money is not too much of an issue, if I can keep the overall spend under £2k that would be good.
    I don't like to add up costs but we're probably talking about £3-4k for mine. Can certainly have been done a lot cheaper though. Worth factoring in that this build will probably take a year or more, and the expenditure is quite piecemeal other than the big ticket items.

    Quote Originally Posted by joe.ninety View Post
    For a floor standing machine, what sort of height should I be aiming for the main supporting frame/structure. i.e how far from the floor do most people make the actual bed of their machines?

    Now I know that no 2 of us are built the same and what's suitable for someone who's 6'6" won't be approprite for Peter Dinklage, but I'm a pretty average 5'10" so what would be a good height to choose? What heights do those of you who are around that height use, and use comfortably?
    As you say, depends what is comfortable for you! I have a standing work bench in the garage which is a really nice height to work at, so I just designed the frame to suit that same height. I think it was around 90cm, but I'll check later and edit this post.

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  4. #3
    Quote Originally Posted by joe.ninety View Post
    I hadn't really thought of doing this as construction of anything still seems a long way off, but as Jazz said a BL is a good way of keeping all related content and stupid questions together, 'stupid' is my addition, not jazz's ;-)

    Like most people, I've been lurking for quite a while and whilst I feel I'm starting to get an idea of what I want, it seems that my path diverges upon the turn of every corner and I'm left feeling overwhelmed at the complexity of making so many decisions.
    Wise choice and over time you'll see why it's best to ask questions all in one place that relate to the machine your building.


    Quote Originally Posted by joe.ninety View Post
    Ideally, I'd like a machine that has a cutting capacity of 1.2m X 0.8m but I'm also looking at the possibility of using it for Aluminium (I'd like to be able to use it to machine any parts and plates for future machines/upgrades) but I'm worried that in trying to make the machine at this particular size, that I'll end up compromising things and that it will do neither well unless I throw a lot of money at it. Whilst money is not too much of an issue, if I can keep the overall spend under £2k that would be good.
    With 2K you can just about do it but you will have to be very careful with what you buy and where from. First off forget buying things like Rails and ballscrews from inside UK or EU. They will need to come from China if you want to do it the cheapest way, but don't be put off by this because if you bought them in Uk then chances are they came from China anyway and marked up 300%.

    Regards the structure then cheapest way to build a strong machine is to use steel for the mainframe and epoxy the rail mounting surfaces for accuracy. The gantry can be built from steel but it's simpler to use Aluminium Profile and makes mounting rails etc very easy.

    The best advice I can give you don't buy anything until your ready to build and don't buy any electronics until needed.

    Next would be don't try to reinvent the wheel. Machines like what Andy and Joe Harris built which use the L shape gantry design and high frame sides work very well, I know this because they are mostly based on my original design which I've built dozens of machines using that are used to cut all materials up to aluminum and brass. Often by users running a small business.

    Finally don't be shy or worried about asking what may feel like stupid questions, they will have been asked before.

    Good luck.

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  6. #4
    Ok,

    Just trying to come up with a list of possible suppliers for bits,

    So far I've got the following...

    Linear Motion & Ballscrews etc. etc: - Fred @ BST Automation

    Aluminium Proflies: KJN

    Aluminium Tool Plate: Seems like lots of possibilities.

    Steppers: Undecided - But I'm assuming that I'll be using the Closed Loop variety

    As far as motors are concerned, what do people think of the kit that Stepperonline sells. They seem to be very competitively priced, and I've seen that they have been mentioned in previous threads towards the start of last year. Are they a good supplier of decent kit or to be avoided.

    Cheers

  7. #5
    I think some people use Motedis for Profiles. StepperOnline / CNC4YOU / Zapp for the steppers & drivers.

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  9. #6
    Am I correct in thinking that

    BK/BF12s are for 1605/1610 Ballscrews

    and that

    BK/BF15s are for 2005/2010 Ballscrews

    Also, I don't see many builds using the other variety... the FK/FF type. Is that because the BK/BFs offer better performance or is it down to costs?

  10. #7
    Quote Originally Posted by joe.ninety View Post
    Am I correct in thinking that

    BK/BF12s are for 1605/1610 Ballscrews

    and that

    BK/BF15s are for 2005/2010 Ballscrews

    Also, I don't see many builds using the other variety... the FK/FF type. Is that because the BK/BFs offer better performance or is it down to costs?
    Yes BK12 = 16mm BK15=20mm

    Regards the FF then they are a different fitment where they don't actually use a block that you bolt down. Instead, they bolt directly to something which is usually machined.
    For instance, you would use them in situations like where you would machine a hole in the gantry sides and bolt the FF block thru the hole directly to the gantry side, you can gain a little extra travel this way. The downside is you have very little room for adjustment or error so require careful planning and accurate machining.

    I use Motedis for my profile, they are cheaper than KJN, esp in regards to T-nuts, etc and usually quicker also a lot more accurate cutting.

    Regards the motors and drives then I'd definitely suggest going with closed-loop but you need to pay careful attention to the Max voltage as a lot of the NEMA 23 sized kits use 50Vdc drives which means running around 45vdc which doesn't make them overly fast. Ideally, look for drives that allow 80-100Vdc or 50-70Ac.
    AC drives are simpler and cheaper because you only need a transformer, where a DC requires a Transformer. Capacitors and Bridge rectifiers to make up the PSU.

    I use Lichuan closed-loop systems on all my machines now.

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  12. #8
    In regards to carriages, I understand that Hiwin is the brand of choice but I just wondered when you would chose to use the W kind, with the side flanges as opposed to the regular square type? So when for example you'd chose to have HGW15CA or HGWCA20 instead of the what seems to be the more common choice of HGR15CA or HGR20CA.

    Also, is it common to have the 20s on the X & Y Axis' and have the smaller 15s on the Z? This seems to be quite a common choice

    I've been watching this video series on YT and that was what got me thinking about the 'W' carriages, as he uses the 'W' variety on his Z axis and his Y, but the 'R' variety on his longest X axis...

    https://www.youtube.com/playlist?lis...yCkJLcRBChdojC

    Finally, are people happy to go with the self-made ball screws that Fred @ BST supplies, or do people still stick to Hiwin branded wherever possible?

    Cheers

  13. #9
    Quote Originally Posted by joe.ninety View Post
    In regards to carriages, I understand that Hiwin is the brand of choice but I just wondered when you would chose to use the W kind, with the side flanges as opposed to the regular square type? So when for example you'd chose to have HGW15CA or HGWCA20 instead of the what seems to be the more common choice of HGR15CA or HGR20CA.
    Ok well first HGR is the rail. HGH15CA or 20CA are the Slim carriges.
    When to use the W or wide carriage depends on the design. Personally I always use the W on the X & Y axis when ever possible and Slim type on the Z axis to save room. If I have plenty of room on the Z axis I'll use the W type again because being wider gives that little more support.


    Quote Originally Posted by joe.ninety View Post
    Also, is it common to have the 20s on the X & Y Axis' and have the smaller 15s on the Z? This seems to be quite a common choice
    Regards 15 or 20mm on the Z-axis then I strongly urge you to go with 20mm. The 15mm is fiddly and mean you have to have big standoff spacers or machine deep into the rear plate. 20mm rails and bearings give you much more support which you need in a Z-axis.

    To be honest, only partly watched the video and didn't see his other machine but he made comment to the rails on the front plate being stronger.? This isn't strictly true and it does depend on the type of cutting your doing and the length of the tool being used and the machine design.

    I've built machines small and large using both methods and there's very little difference between them when using short tools, as the tools get longer the rails on the front start to have a slight advantage because the Z-extension reduces. However, this only applies up to a point because it also limits the length of tools and the material height you can use. Whereas the other method with rails on backplate allows much longer tools to be used, it allows much taller material to be used and still use long tools or drills.

    So here's where machine design comes into the mix. With the rails on the front plate then because it limits material and tool size due to the fact it can only lift the spindle up until the rails reach the bearings, meaning the tool and spindle hang below the gantry. This means the gantry sides need to be taller if you need to cut taller material with longer tools. This weakens the machine and takes away any advantage it offers over the other method, which as I say isn't a great deal.

    Whereas the rails on rear plate mean that the spindle can be lifted high up the rear plate so the tool clears the bottom of the gantry giving the full height from bed to underside of gantry even with a long tool. This means you can make your gantry lower and still have the same material clearance as the other method but it makes a much stiffer machine and better cutting so eliminates any advantage the rails on front plate offers.

    So as you see there's more to it than just bearing type.!

    Quote Originally Posted by joe.ninety View Post
    Finally, are people happy to go with the self-made ball screws that Fred @ BST supplies, or do people still stick to Hiwin branded wherever possible?
    Fred is a great guy to deal and I fully recommend him, tell him Dean sent you and it might help on the price. Also, I suggest you invest in some C5 grade ballscrews and ask for the Better BK/BF bearings which I believe are C3. These are more in line with Hi-win grade ballscrews.

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  15. #10
    Do the external dimensions of BK/BF blocks vary by manufacturer or are they standard dimensions dependent only on rail diameter?

    Cheers

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