Not on your own.....Quote:
Originally Posted by John S
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Not on your own.....Quote:
Originally Posted by John S
Been playing with a few idea's and I have attached a quick render and also a 3D PDF file to help you understand what I am thinking.
To open the PDF you may need the latest Adobe reader V9 (free to download), you will be able to spin it round, zoom in and out and take it apart. Easier than doing loads of drawings from various angles.
I have used the IGUS N profile 27mm for all the slides, not 100% sure that this is the way to go though.
This is just a concept drawing, 18mm MDF all round and I have tried to make everything as close to actual size as possible so that I can get an idea of how it will fit together.
Anyway take a look and let me know your thoughts, I have a few things that I am not happy with but it would be interesting to get some more opinions.
Hi Steve,
It’s looking good, I’ve not replied but I’m following :).
I think one thing that sticks out as a possible concern to me is that, when I built my rockcliff machine the 13x13” Y Table (the bit you put your work on):
Attachment 2218
Started to bend and go banana shaped in a very short amount of time. I did have an unnecessary pocket along the length and I think this helped it on its journey to becoming banana like. My concern is that yours may do the same, an option to stiffen it all up maybe to add some ribs under the table the same shape as the Y Axis ball screw floating end plate in your model.
I would prefer if the machine was a flying gantry type as well, if you think about it the design at the moment needs a bigger foot print then if it was done as a flying gantry type.
So I’m thinking, take off the support footer for each of the gantry side plates, mount them at each end of the Y Table (possibly even double them up), use two lengths of MDF that run underneath/in-between the rails and Y Axis plate, this would then hopefully give you the clearance for the ribs.
Just my observations mate, what do I know :confused:
O nice Z Axis design as well, i like it :cool:
I have a suggestion about sealing MDF.
As most of us know from experience (there are a lot of MDF 'bananas' around), MDF is hygroscopic and will absorb moisture from the air. If it absorbs water from the air unevenly and/or the MDF sheet is not a uniform thickness it will warp. Sealing it all over against moisture absorption could be the answer to preventing it warping.
One sealant could be plain old boiled linseed oil which, if put on correctly will polymerize like plastic and it’s also a little flexible as well. It's also cheap.
Clean the dust of the MDF. Round off any sharp corners if possible.
The first coat can be boiled linseed oil diluted 50:50 with turpentine or white spirit put on fairly quickly (to prevent warping). Wipe it on with a cloth and leave to dry (supported on blocks) in moving air away from heat or direct sun.
2nd coat can be 75% boiled linseed oil 25% turps. wiped on quickly with a cloth. Don’t leave pools or surplus on the surface - they won’t dry properly and won’t polymerize.
These 2 diluted oil coats will go into the MDF and provide a better key for the next coats.
Next use neat linseed oil wiped on with a cloth and again taking care to remove any surplus. The MDF should then be fairly well sealed but the more coats you put on the more effective and long lasting the seal will be. 3 or 4 more coats at least of neat linseed oil wouldn’t go amiss.
I know it’s time-consuming but people without much money to spare would rather spend their time and it’s low tech.
Don't seal moisture inside damp MDF. Make sure it's as dry as possible and the ambient air isn't humid either.
A very light sanding with fine glass paper between coats will help to key the coats but vacuum-clean the dust off.
Remember safety. Wear rubber gloves, don’t breathe in the fumes or dust, dispose of oily cloths safely - either in a bucket of water or wash them out thoroughly and dry them outside. Oil-soaked cloths are a potential fire hazard.
I'm not suggesting you try this on an important or complex part. Try it on a test piece first.
I hope this helps and that I'm not 'teaching people how to suck eggs'. Let me know if I am and I'll shut up. If anyone tries it I'd be interested in how well it worked for them.
Regards.
What about the waterproof versions of MDF for critical components. ?
Steve, up on our industrial estate, makes custom furniture to fit your house using MDF and wood mouldings. He always uses a green coloured variety of MDF because he can't afford to have it warping.Quote:
Originally Posted by John S
That sounds interesting ... Fancy a stroll along there if the weather is nice Robin? ... :whistling:
Only joking ... I shall google and ask a chippie type contact for further info.
Can I ask where you found this price? I was looking at the "piece of angle skate" option but couldn't find a price like this??Quote:
Originally Posted by mel_earp
Thanks
Paul
Has anyone ever built any of these skate bearing linear guides and had decent results?
Just don't like the look of them but not had any experience with them either.
The cheapest I have ever seen is £2.99 and that is for 10. Obviously you are not going to get top quality for that price, but I bought a set for a fiver for something other than CNC and they work just fine (light duty) - smooth as silk and no play.
I haven't tried skate carriages, but I go on what people write and look for majority views and counter views. On the US CNCZone there are dozens of builds using this method and many look really good for a cheap build. I am quite surprised no-one here has chirped up to say they have done it. Also, the original buildyourowncnc uses this method, but they have changed to V-Groove bearings. Those videos might be of help to you. Some bits look a bit crude, but there is also some good stuff.
Thanks,
I've found some in Nottingham on fleabay. I contacted the guy and I can go and fetch them :) That way I can see what they're like before I bye and also save on shipping!
Hi Steve, interesting project. You must have plenty of spare time :smile:Quote:
Has anyone ever built any of these skate bearing linear guides and had decent results?
Just don't like the look of them but not had any experience with them either.
I've not used the skate bear guides but share your concern. To me the results would seem to be heavily depend on the workmanship and there could potentially be a lot of alignment issues:eek: (the poor results might put off some beginners)
What I do know is that the twin 25mm unsupported rails that I was going to use for my mill used a solid bronze bush on 1 side and 2 opposing skate bearings on the other and it always seems notchy when they are adjusted up tight. The solid bushing was silky smooth tho.
I know that unsupported rail are always shot down because they flex but considering the aim of this project and the small spans I'm sure it would be the best option to balance ease of use, cost and performance. There is the option for solid bushing or ball bearings that would provide the flexibility required.
With regard to using mdf, when I used to work for a car audio shop we built lots of custom Sub boxes and it was always apparent how much stronger the structure was when the joints were routed, glued and screwed so I would defiantly recommend this form of construction. if you dont mind me interfering I can help with options for stiffening the bed to keep Lee happy :heehee: (easy. dont remove a big chunk of material at max bending:rofl:)
Better shut up now, later
Another method that appears to be popular when joining MDF at 90deg is to use the 'Brass' rods and screws, as used in beds (the kind you sleep in) ...
Just a thought :naughty:
If you are going to use skate bearings why not use good old hexagon bar stock to beef up your bearing faces?
Good idea. With the more usual angle configuration you end up having to mount the carriage on a 45 deg chamfer of some description. With this, you get the bearings at 60 deg and a flat on top/bottom. to mount the carriage.
With the bearings being at 60 deg, they would be best run on round or hex rail rather than 90 deg angle.
Also, does this mean that you are going to have to drill and tap the bar stock to fit the bearings? No big deal for you guys, but might not suite a beginner.
I'll refer you back to the first post "Also I will be prepared to either manufacture myself or get components made that people are struggling to make, not all the components but just the parts which will be difficult to make at home. How much will these cost? Not as much as you think! I am not here to earn a living from this just give people a chance to get started." This would be a good example of where others could help out. However even a beginner would benefit from investing a few quid in a cheap drill press adaptor to get a bit of accuracy! Drilling and tapping hex bar stock wouldn't be that difficult.Quote:
Originally Posted by mel_earp
I understand the points you make Irving. If the target audience is the beginner then surely it is worth taking the views of the beginner - and I am totally a beginner who has made nothing CNC, just read a lot. From my perspective wood is good and metal is difficult (can't think of a suitable rhyme). For others it will be different and they will prefer metal to wood.
The common skate carriage is easily made because in the basic form you saw a bit off, drill four holes and bolt the bits together. As you go more complex then more chance of error or frustration.
And I do have a drill press.
Careful ... SWMBO bought me one of those from B&Q... the 43mm euro collar would not grip a 43mm drill with a piece of 240 grit paper wrapped around it and also the casting was 3deg. off centre. It may have been a Friday afternoon special, but Wolf or Draper offer better quality (for a price)Quote:
Originally Posted by irving2008
I've been thinking about my own build plans and how I'm going to run the bed. I'm considering the skate method as it's simple and cheap. I then thought about using v-groove bearings and running them directly on top of a piece of angle. My sketch-up skills aren't great but hopefully you get the idea. It would be a moving bed with the top bearings attached to the gantry. It's only an idea I had today so they may be obviously floors that I'd not considered yet but it may be worth experimenting with?
http://i175.photobucket.com/albums/w...rooveguide.jpg
Sorry not replied for a while but I am up to my nuts in other jobs that needs to be done before I get time to play, one of them being fitting a new bathroom... seemed like a good idea at the time..!
Anyway, I should get a few hours at it again later this week so fingers crossed and keep the idea's coming because there are a few good one's in there.
Can anyone put tiles up??? only a couple of hundred.... will keep you fed with tea and hobnobs... Give me some time to do something that I enjoy doing instead.
Off topic - Ah, I take it you've not done one of those before :) there's always a first time... never (in my book at least) a second one... this time i got a couple of nice Polish guys, nicknamed Radish and Leek (thats my nearest pronounciation of their names) who did a blinding job in a week that would have taken me months (plumbing, tiling, electrical - I can do it, just not as quickly) and that included keeping building control happy...
Never managed that............................Quote:
Originally Posted by irving2008
Heheh i'm in the middle of doing my bath room Steve, need another 3 box's and im done!
A good idea to you or to her? There is a way out.Quote:
Originally Posted by HiltonSteve
I am a disaster at home improvements, paint flies everywhere, she'd never ask me to do tiling.
She used to make me do car repairs in the cold and rain, eventually I put the car together without the head gasket, gritted my teeth and turned the key. Cost me £600 for new valves but she never asked me to do car repairs again. Money well spent.
Sorry, I couldnt ever do that to a car... thats sacrilege! Although working on cars in the rain is something I do try to avoid, I do recall changing the gearbox on my 1965 Triumph TR4 in 6" of snow... mad or what?Quote:
Originally Posted by Robin Hewitt
But I don't drive bird magnets like you do, this was utilitarian.Quote:
Originally Posted by irving2008
I hate driving, bores me to tears :rolleyes:
Wots a bird magnet ?
How many can you get in a 3 tonne truck ?
Unless you can get a full size set of gas bottles into a vehicle without struggling, it's a waste of road tax.
I was sent this link to look at as a method of using telescopic drawer slides for linear guides ... I must admit I had not thought of using them like this ... http://imagebin.ca/img/tt45r26C.jpg It may be worth considering, but I will leave it up to those with superior knowledge to pass judgement ...
Cheeky b*stard. No it is not!!!!!!!!!!!!!!!!Quote:
Originally Posted by irving2008
Have I been gone that long everyone thinks i'm dead??? John, Steve, Lee????Quote:
Originally Posted by HiltonSteve
I hear knocking... Is there someone there???:eek:Quote:
Originally Posted by michael
welcome back... it seems a while... lol
Yup.............
.
As a bewildered newbie I would just like to voice my support for this project - and from my perspective the original proposed target cost of approx £350 seems reasonable, particularly if we can spread it out as we build the router over time. Thanks for your work on this and I wait with excited impatience to see how it turns out, and the chance to be a guinea pig builder for you...
I am also a newbie and I expect that when I build my machine it will cost me £1000+ because I want it as good as I can get it, when you consider this is done over a year its not to bad, some hobbies cost money, a lot of money that's the way it is but having said that, if someone can build a good machine below £1000 please give me your tips!!
A "good machine", as in 'commercial', would have a cast iron gantry.Quote:
Originally Posted by gorbo
If you don't have chums at the foundry, a cheap alternative would be box section iron filled with concrete and don't be mean with the cement when you mix it.
Heavy kills vibration, concrete resists bending when you load it.
1 pound force will accelerate a mass of 32.16 lbs at 1 ft/s/s.
1 Newton will accelerate a mass of 1kg at 1 m/s/s
A 1Nm motor on to a 5mm pitch screw will give you 125N thrust.
Hi all, this is my 3rd revival of interest in cnc, story so far: That's cool but it's expensive, interest wanes. That's cool and doesn't have to be expensive but it's complex, interest wanes. Maybe I could make a few bob from this, interest rises. lol
Someone that knows someone close to you looks at something produced on YOUR cnc machine and says... I want one...how much? When this happens, all of our expense is justified. iow, it's not the making of a few bob that is the priority, it's the being able to use the motive of making a few bob in order to do what you wanted to do anyway that is important. Cue Douglas Adams and the software that gives you reasons for getting whatever it is that you want. (I've forgotten what that software is called.) :)
So what does this machine make that other people want? I think this has to be decided first.
Whatever newbie machine is being designed, it has to make stuff that other people want or there is not much point to doing it, might as well build a toy robot that only does somersaults or buy a Lego Mindstorms.
So what can this cheapo newbie machine make?
[btw, I hope that I'm not being seen as negative, I think that it's a great idea.]
Not yet familiar with the site, the pic is of a £95 milling work table that looks like it could do with a couple of stepper motors, there's your X-Y axis. Choose a corner of the workshop with 2 load bearing walls, build a strong shelf for the work table and add a cross section for the Z axis up above. Just a thought.
So, is that bathroom done yet? has this made any progress?Quote:
Originally Posted by HiltonSteve
Bathroom done...Quote:
Originally Posted by CraigRK
And new single storey extension on the back of the house together with a new kitchen. The next time the wife comes up with one of these ideas then I must either talk her out of it or pack a case for her.
Thrown everything out the workshop so it no longer looks like a builders merchants and swept the floor, you can now walk round without breaking your ankle...
May look at getting something moving again on this one, but the one thing that stopped me before apart from the DIY was people saying that it was too expensive. Building any cnc machine is time consuming and will mean you having to put your hand in your pocket a few times but look at it as in investment, I made a few small plaques out of a bit of oak last week which took me a couple of hours, sold them for £120...😊
Not just about making money but also learning something along the way.
What sort of price for building a small MDF machine do you think is reasonable?