DIY milling machine

[VicParticipant @vic]

Posted by Jelly on 11/02/2023 20:10:18:

The Fobco is built very solidly, out of substantial castings, and uses a very rigid spindle design, which includes a pair of angular contact bearings preloaded against each other, which is not unlike the arrangements used in many modern "hobby" milling machines.

It’s no more solidly built than my Progress number one or thousands of other old drill presses out there. 😉

[VicParticipant @vic]

Posted by Ady1 on 12/02/2023 00:06:55:

I should add one caveat, you MUST use a collet to hold a milling cutter, a drill chuck simply won't hack it, the side forces mean your cutter will eventually wander into or out of the chuck jaws and mess the job up

Agreed, up to a point. I’ve been lazy on occasion and rather than swap out a drill chuck for a collet chuck I’ve just popped a milling cutter in there and carried on. I wouldn’t attempt it with a large cutter or milling steel but I’ve got away with it quite a few times. I’ve actually got a job in the vice at the moment and I’ll be doing just that! It’s only a small cut in soft material so no drama.

[JellyParticipant @jelly]

Posted by Vic on 12/02/2023 11:13:27:

Posted by Jelly on 11/02/2023 20:10:18:

The Fobco is built very solidly, out of substantial castings, and uses a very rigid spindle design, which includes a pair of angular contact bearings preloaded against each other, which is not unlike the arrangements used in many modern "hobby" milling machines.

It’s no more solidly built than my Progress number one or thousands of other old drill presses out there. 😉

Neither are widely available outside the UK (considering Andrei is in Romania) and certainly not typical of the kind of drill press you'd find if you were looking on a budget today.

 

I actually passed on loads of Progresses and Fobcos before I bought the Sealey because they were selling for a huge price premium (5× or more) compared to other similarly capable modern drills, precisely because they're built to a higher standard than the vast majority of new drills and can command a price point higher than many brand new ones.

So from the economic perspective, a Fobco Star on eBay today would cost £400-700, when there are regularly milling machines which sell for substantially less, which would be a better way to deploy the money.

Edited By Jelly on 12/02/2023 14:39:04

[VicParticipant @vic]

Posted by Jelly on 12/02/2023 14:36:24:

Posted by Vic on 12/02/2023 11:13:27:

Posted by Jelly on 11/02/2023 20:10:18:

The Fobco is built very solidly, out of substantial castings, and uses a very rigid spindle design, which includes a pair of angular contact bearings preloaded against each other, which is not unlike the arrangements used in many modern "hobby" milling machines.

It’s no more solidly built than my Progress number one or thousands of other old drill presses out there. 😉

Neither are widely available outside the UK (considering Andrei is in Romania) and certainly not typical of the kind of drill press you'd find if you were looking on a budget today.

There are probably thousands of similar old bench drills in Europe, why would it need to be a Fobco or Progress?!

[Sonic EscapeParticipant @sonicescape38234]

Posted by Andy_G on 11/02/2023 09:56:01:

I built a router type machine (CNC) with a cheap, air-cooled spindle motor, and it was nowhere near rigid enough. After some re-engineering, it will cut aluminium (fairly happily) and steel (not so happy). It is still not very rigid and I'm in the process of making a new spindle along the lines of your second option.

The cause for the relative lack of rigidity can't be the linear rails? I also wanted to use them because they are widely available but I read somewhere that dovetail slides are more solid.

Thank you for all suggestions. I suppose that a stronger bench drill would work better. After all even with my Bosch drill I was able to cut a steel nut and a bolt. But I want to build one just because I find it an interesting project. It doesn't matter if in the end it might end up more expensive that a used machine. The cost will be spread over a long time.
However I'm considering also the option of buying an used milling machine in bad shape, if the cost is reasonable, and to restore it. If it is a serious machine, >600kg. That would be and equally interesting project I think. In my region there are often in the used market old Romanian milling machines. My favorite is this one, a FUS22:

It weights 800kg. But it costs 2000€. Because the seller insists in selling it together with a large rotating table, a divider head and an additional slotting head. If they are in worst shape, like what I'm looking for, they end up in the scrap yard not on Internet. And even without accessories they don't drop bellow 1500€. This days I'm also looking for a lathe and such a milling machine would consume too much from that budget.

In my ignorant view, all I need is a way to move the spindle vertically as rigid as possible. I'm happy even with locking the spindle after I set the height. To be more rigid. I don't plan to adjust it during the milling. It is not a CNC.
The rest is relatively easy. For the frame I can weld something heavy enough. Steel is cheap. I dropped the requirement to be able to move the machine alone. I can build it directly where it will stand. There is plenty of space around. It is also a well ventilated place to use MMA welding there. The electronics part like speed regulator is not a problem.
I started some talks to see how much it would cost for somebody to drop a large boulder in my yard. I heard that some high end milling machines are made from granite. I could carve the boulder outside and then move it somehow in the garage. But this is not my first choice. Or at least not yet

[JellyParticipant @jelly]

Posted by Vic on 12/02/2023 16:57:04:

Posted by Jelly on 12/02/2023 14:36:24:

Posted by Vic on 12/02/2023 11:13:27:

Posted by Jelly on 11/02/2023 20:10:18:

The Fobco is built very solidly, out of substantial castings, and uses a very rigid spindle design, which includes a pair of angular contact bearings preloaded against each other, which is not unlike the arrangements used in many modern "hobby" milling machines.

It’s no more solidly built than my Progress number one or thousands of other old drill presses out there. 😉

Neither are widely available outside the UK (considering Andrei is in Romania) and certainly not typical of the kind of drill press you'd find if you were looking on a budget today.

There are probably thousands of similar old bench drills in Europe, why would it need to be a Fobco or Progress?!

The original point being that it's important to know how the spindle is assembled and pick one with a angular contact bearings which are sufficiently preloaded…

That it looks similar to a British one is irrelevant, it's knowing the manufacturer chose to build the drill with a suitably rigid bearing arrangement.

[Sonic EscapeParticipant @sonicescape38234]

Posted by Vic on 11/02/2023 14:17:31:

This thread may be of interest.

**LINK**

I knew about epoxy frames. It was one of the first options that I investigated. But I'm not familiar with the materials. What I found here is very expensive for the volume required.
But how about some high grade concrete? A cubic meter of the strongest commonly available concrete here is 80 euro I think.

if I had known that I would be interested in milling machines before the house was ready I could alter the project to incorporate a milling frame. And I would have lived in a milling machine 

Edited By Sonic Escape on 12/02/2023 21:12:31

[HuubParticipant @huub]

Posted by Sonic Escape on 12/02/2023 20:34:32:

However I'm considering also the option of buying an used milling machine in bad shape, if the cost is reasonable, and to restore it. If it is a serious machine, >600kg. That would be and equally interesting project I think.

I think this is a better choice than building one without the proper tools and knowledge. When you have done the first one, you have the tools (milling machine) and more knowledge to build one from scratch.

For starting, as a learning project, any half decent milling (small) machine will do. The parts of industrial machines are very heavy and hard to handle.

[Andy_GParticipant @andy_g]

Posted by Sonic Escape on 12/02/2023 20:34:32:

Posted by Andy_G on 11/02/2023 09:56:01:

I built a router type machine (CNC) with a cheap, air-cooled spindle motor, and it was nowhere near rigid enough. After some re-engineering, it will cut aluminium (fairly happily) and steel (not so happy). It is still not very rigid and I'm in the process of making a new spindle along the lines of your second option.

The cause for the relative lack of rigidity can't be the linear rails? I also wanted to use them because they are widely available but I read somewhere that dovetail slides are more solid.

 

No, the lack of rigidity was in the spindle itself – the frame of the machine is ~6kN/mm measured near the spindle, but the original spindle itself  was only ~0.8kN/mm, and the re-worked spindle was ~2.5kN/mm. I'm in the process of building a new spindle which I hope will be stiffer. It's a "rabbit hole"

Edited By Andy_G on 13/02/2023 01:20:40

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