Thomson or Premium Ballscrews?

[ktkg]

I am pricing out a possible SX3 build and wanted to know if there would be a huge difference between the CNCfusion kit #1 with thomson ballscrews and the premium package. There is quite a big price gap it seems.

I do need to be pretty precise, id like to be within a thou when machining. Could this be done with the normal ballscrews?

Also, if I know nothing about milling, do you think I would be able to make my own motor mounts? Or should I just pay the extra $200?

[devers6]

I have the deluxe CNCFusion kit, and I have never been sorry I bought it. Sure, it is more expensive than run-of-the-mill ballscrews and nuts, but to me the peace of mind of not having to constantly be fighting backlash and inaccuracies was worth the extra cost. I realize not everyone has the $200-$300 difference laying around, and sometimes you just have to compromise to make the project fit the budget. But I certainly don't feel the additional cost of the deluxe kit is a waste.

If you know absolutely nothing about milling, you will definitely learn something in the process of making your own motor and ballscrew mounts. You will probably make them 2 or 3 times, and you'll get better each time. You need to be able to measure and cut things to a good level of accuracy; which is a skill you need to learn eventually if you ever hope to find satisfaction in metalworking as a hobby. The things you will need to cut, like bearing pockets and mounting holes, aren't magic - just be prepared to be disappointed in your early efforts and be willing to toss them out and start over; hopefully learning something with each iteration. There is no feeling quite like looking at a piece and knowing you made it yourself.

Any fool can buy perfection - but it takes a true machinist to make it; and isn't that what we are in this for? Look at it this way - you probably won't save much in the long run by making all your conversion parts over buying them. The difference in cost will probably be eaten up by scrap and by however you decide to value your time. So if getting productive in as short a time as possible is most important to you, buy the bolt-on kit. But if you are wanting to teach yourself precision and patience, and you value the learning experience and want to become intimately acquainted with your machine; build it yourself.

The risk is that you might find yourself over your head; and you might get discouraged and end up thinking this hobby might not be for you. If that's true, better to find it out now before you've used up a second mortgage to buy tools. But post here first before you give up - I think you'll find enough encouragement and experience to get you out of just about any jam.

[cyclestart]

A typical spec for a rolled screw is .004"/ft accuracy. The Thomson screws are probably typical. Looking at that, holding .001" over any kind of distance is unlikely. Honestly there's a lot to consider when trying to hold .001" positional tolerance, a good screw is only one part of the equation. Otoh a mediocre screw makes it even more difficult.

[LUCKY13]

I would get the screw & the mounts. You have a lot to learn and getting your machine up and running will be the best way to get started on learning.


All though the guys are right you would learn a lot by making your mounts. But, with the machine running you will get to learn more, and be able to start out at a level that is more comfortable for you ( jump in at your own speed).


Start out with cheap end mills also, you will break many.


To hold a .001 in machine takes skill. The machine is only part of what it takes to do it. With that said the better screws will make it easier for you and you want have to be working on the machine because of slop/backlash in the axis, you can work on parts.


Remember there is a big differance in repeatability, and accuracy. With good repeatability you can get good accuracy if you use your head and know your machine. So screw accuracy is not that much in help ( all though it does help) but having no backlash is golden. The better screws will be quiter, smoother, more durable, less backlash and more accurate so it is worth the expience. You can take the cheaper ones and put work, time & money into them and get them repeatable but its not the place for a beginner to start. If you have other machanical background then that may be different.


Best to get what you need to make the machine run & run good because there will be many other things you need to worry about learning. There is a lot more to all this than it seems when you are new. It will take time & money even when you have a good machine to start with.


Good Luck, Jess

[Matt McColley]

If you want to get the mill up and running and have fun making things, get the kit.

If you want to spend the next year puttering away at making your own mounts and looking for a lathe to machine your own ball screw ends, then diy.

Don't ask me how I know this.