my first build

[wires]

the reason i am looking at this controller is that i have read that it is quite easy to blow a stepper driver, particularly when you dont know what you are doing. with this board that only means you need the driver board and not the whole thing as is the case with single board units.

power supply wont be a problem. like you said, will just keep an eye on the bay from now on for a deal.

with regards to the linear stuff i have come to the realisation that this will not be my last cnc machine. what seems to be the norm here is that you build your first machine and use that to build your second. i know my linear idea is tricky and will take some time to get right but i have lots of time now and i do have lots of patience to get it right. also i am pretty handy with the table saw and router. when i get it modeled i will post some pics for feedback.

i like that TR12x3. the price aint bad either, i might just go for that. it seems i will have to get the ends turned down to fit bearings and coupler. i will have to find someone local to get that done, might know a guy.

i had a good look around the dryline site but i cant decide which size rails and bearings i need. guess thats just my lack of mechanical training.

with reagards to 2e0poz points i do see the logic in buying the propper stuff and under normal circumstances (have a job) i would definatly just spend the £500 on linear bearings and be done with it but i really dont have the cash at the moment. that might change in the future but for now this idea of mine wont cost much to try. i already have mdf and i have a load of ball bearings which might do the job, all i need is some alu angle and a lot of time (being unemployed, time is not a problem). i am not sure i know what you mean about mounts, could you elaborate?

the reason for not doing any construction right now is there is no point in cutting a load of mdf only to find the design change and stuff going in the bin. in my mind its better to just get the design finalised and then as 2oepoz says, you get it made in less than a week.

i can see the advantages of propper linear bearings but i just cant afford them at the moment plus i am not convinced they would really make that much difference to my machine given i will just be cutting mdf or ply. assuming i can get my the home made linear tight engouh and pay close attention to minimising chassis flex i think it will work out fine.

like i said this is my first machine and it will have specific uses. no doubt i will make another more elaborate one soon after this is completed and if i have a job at that time i will put all the propper stuff into it.

thanks for all the advice guys even if i dont take all of it, its just a budget thing. i am getting pretty excited about all this, keep having ideas flying around my head. cant imagine what i will be like the day i fire her up

[irving2008]

i like that TR12x3. the price aint bad either, i might just go for that. it seems i will have to get the ends turned down to fit bearings and coupler. i will have to find someone local to get that done, might know a guy.

You can turn them down with the help of an electric drill, a file and some emery paper and a couple of 12mm ID ball races in some MDF pillow blocks. Support the TR12x3 in the pillow block bearings, suitably spaced, the one at the business end leaving say 50mm showing. Chuck the far end in the drill and whizz it at 1000rpm, then use the file to shape the end to a near fit and finish with the emery paper, doing trial fits on the appropriate bearings or measuring as you go...

You might find the use of a grinder to take the hardening off the surface helps, a dremel or similar is an alternative to a file and can be quicker...

At least one member has used this technique successfully...




Of course if you know a man with a lathe...

[wires]

i have been trying to think how i could do that myself, that sounds simple enough. i have a bench grinder and vernier calipers.

i do know a friend of a friend who works in a tool making workshop, might see if i can call in a favour when the time comes.

being a noob i am not sure what a pillow block is. do you mean a small square of mdf with a hole for the bearing? you then make a hole larger than needed in the machine chassis so that the pillow block can be moved to line it up perfectly?

also, if i am going to get some thrust bearings i need to understand them a little. my understanding of thrust bearings is that they handle the load laterally along the length of the screw but they have no ability to handle side to side loads. do i need a ball bearing and a thrust bearing in each pillow block or am i missing something?

[irving2008]

...being a noob i am not sure what a pillow block is. do you mean a small square of mdf with a hole for the bearing? you then make a hole larger than needed in the machine chassis so that the pillow block can be moved to line it up perfectly?

A pillow block is just a bearing mounted in a carrier, usuall cast or pressesd steel with ears to bolt down with. you can buy them ready-made or, for this purpose, two 12mm id races mounted at equal height in some blocks of MDF screwed to an MDF base will suffice... its only to provide some support for the leadscrew while its being worked on so moderate accuracy only needed...

also, if i am going to get some thrust bearings i need to understand them a little. my understanding of thrust bearings is that they handle the load laterally along the length of the screw but they have no ability to handle side to side loads. do i need a ball bearing and a thrust bearing in each pillow block or am i missing something?

For the actual machine you need a bearing block which retains the leadscrew radially (ball race) and axially (2 x thrust bearing), alternately you'd use 2 x angular contact bearings but these are hard to find in small sizes. See the pic for a guideline

[wires]

ah i see. so if it is supported by thrust bearings either side of a ball bearing on the drive side of the screw there is no need for a thrust bearing on the other end, just another ball bearing. i think if i am going to go that complex on the machining of the ends of the screw i will just get someone with a lathe to do it right.

thanks for clearing that up for me, i was wondering how exactly i would do that. one more thing decided

[jonm]

hi wires
if you look at my build , i turned down 12x3 trapeziod screw
with a drill , grinder and file it turned out really well

i have the system 3+ board from diync also a power supply
support from roy is first class

i built my router from mdf to start with but i am now in the process of rebuilding in aluminium , should have went the alu route to start with

[Swarfing]

Sorry I totally missed the point of the cash flow issue and i can appreciate your position. I did explore the use of patio door rollers as slides. I buttered up a couple of window fitters to have a butchers at some old patio doors and i was pleasantly surprised at what i still believe to be a viable idea for a low budget machine? just a thought or you could just go for plain old Bronze bushes?

Paul