not so ‘run of the mill’?

[An OtherParticipant @another21905]

This turned up in my inbox today:

https://hackaday.io/project/202166-heavy-desktop-mill

not really ‘heavy’ but nonetheless interesting – perhaps this is an example of the sort of the sort of project which would attract new readers.

[BazyleParticipant @bazyle]

It is a small gantry mill about the size of the one featured in the recent issues of MEW – pictures minimal description. Website imposes cookies on you so haven’t investigated.

[JasonBModerator @jasonb]

Not your usual Gantry mill as the spindle does not move along the gantry, more a two column mill where the table moves in X&Y like a regular mill and the “head” if on two portals rather than a column

If you want one without Cookies, Sebastian End has now got the downloads for his machine available, click the link in the description below the video. Also now with English voiceover.

[Clive FosterParticipant @clivefoster55965]

So more like a baby planer mill then.

Which always seemed to me to be a more rigid way of going about things than the usual moving gantry set-up. Albeit at the cost of needing a space covering almost twice the length of the table. Which is, in practice, little different to the way a conventional mill needs room for the table traverse.

I’ve been expecting this layout to be picked up by small CNC machine builders ever since DRO scales became affordable as it has several engineering advantages over the usual style which is basically converted manual machine. A manual version is, of course, quite impractical so there isn’t the production advantages of sharing existing castings. The manual equivalent would be effectively conversational numerical control with the machine driving the cuts to electronic stops defined by by putting the appropriate travel distances in.

Clive

[BazyleParticipant @bazyle]

Here is another fairly detailed build. I think he may have posted on here.
https://misterg.org.uk/cnc-introduction/

[JasonBModerator @jasonb]

Clive, not really like a planer as the main X length is parallel to the “gantry” so it does not pass under it like a planer.

It also has hand wheels if you want to use it manually

[Clive FosterParticipant @clivefoster55965]

Jason

Thanks for the better view.

So basically just an effective way to make built up from (mostly) extrusion construction stronger and more suitable for the stresses of proper metalworking. Nice job for sure.

Given that a “bench top” planer mill with a capacity approaching that of a Bridgeport has been a long standing “if I were younger” project desire it would be interesting, and more age appropriate for me, to see what could be done using that style of construction. I figure maybe double the work area of that machine before it runs out of stiffness if High Speed Machining techniques based on small cutters running very fast at low step-over were used.

Nearing 71 I’m supposed to be finishing and cutting down on the project list not adding to it but would be an interesting 6 months!

Clive

[VicParticipant @vic]

I’ve seen this type of extrusion many times before, but nothing this wide. Any links for something like this or a suggestion of a good search term? I’m thinking it may come in handy for future projects.

[Graham MeekParticipant @grahammeek88282]

Hi Vic,

In my Toolmaking career I built many assembly Robots using this type of construction medium. We mostly used “ITEM”, but for Audi they insisted we used “BOSCH”. The latter was much more expensive, so be sure to be sat down.

Regards

Gray,

 

[JasonBModerator @jasonb]

Vic, google 2080 teeslot for the small one and 30120 teeslot for the large, you can also get 40160

[VicParticipant @vic]

Great, thanks. I did have some bookmarks for stuff like this a few years back but can’t find them now.

Edit: I’ve added this to my Amazon wish list for future reference. 😉

[Clive FosterParticipant @clivefoster55965]

Those profiled extrusions are very useful but some care needed with the economy range versions which frequently aren’t as flat, straight or true as the naive customer might hope. Rarely bad enough to be an issue when building  simple, not too large things, from basically square or simple rectangular profiles but you should check. Machine building quality cannot be take for granted.

It’s remarkably difficult to extract actual straightness and flatness tolerances from the online catalogues. The optical equipment suppliers, who might be expected to source high quality extrusions, seem to claim between ± 0.1 and ± 0.2 mm per metre. 25 or so years ago when I got involved with the stuff I was “less than convinced” and rejigged sections of kit built by less discerning co-co workers with cast iron!  For ordinary commercial extrusions up to ± 1.5 mm per metre seems to be acceptable in some quarters.

Having paid a small fortune for the good stuff handle it carefully. It’s easier to bend than you might expect. Especially the basic un-heat treated stuff which relies on age hardening to reach its specified stiffness. There should be a material state code. T3 is basically quenched straight out of the extrusion press and ages to T4. T5 has proper heat treatment process and ages to T6.

When it comes to the wide ones like those shown by Vic you get what you pay for and the high end brands are far more reliably flat. Re-working an inadequate section to machine table standards could be interesting, and not in good way.

Clive

[JasonBModerator @jasonb]

If you look at Sebastian’s one that is why he says you may need some shim tape when fixing the linear rails to the extrusion so that they are not distorted an dcan be set true to each other.

[BazyleParticipant @bazyle]

To tie things together a bit this is a link to a previous thread on the ME CNC  articles https://www.model-engineer.co.uk/forums/topic/sable-2015-desktop-cnc-engraver/
and a thread on spindles https://www.model-engineer.co.uk/forums/topic/multiple-bearings-in-spindle/page/3/
With regard to contributors to the latter link it would be interesting to hear more from Steve C and Andy G both of whom might be persuaded to write stuff up for ME&W.

[An OtherParticipant @another21905]

No end of aluminium extrusion on Aliexpress and BangGood. Try also searching for ‘aluminum extrusion’, using the American mis-spelling. My guess is most suppliers source this stuff from China.

[simondavies3Participant @simondavies3]

There was a guy some 20 years ago who built the CNC mill to end all mills using (from faded memory) lots of surplus extrusions.

the site was “5bears dot com” which has obviously been lost and now points to a porn site (don’t they all – groan).

however trawling through the internet wayback gives lots of good stuff and was very readable – this particular page shows the use of extrusions

http://web.archive.org/web/20051023205325/http://www.5bears.com/cnc.htm

Simon

 

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