Gallery, Projects and General > The Design Shop
Keeping the head from turning on a cheap mill
CrazyModder:
--- Quote from: Arbalist on December 27, 2013, 05:02:14 AM ---If the rack on the side of the column is fixed both ends it shouldn't move that much. Can you take a picture of the elevating mechanism and rack so we can see exactly whats there?
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The rack is, sadly, not sitting tight in its slot; some people have actually retrofitted a guide there so the column can be moved up/down without swiveling. This is fine - when moving the column, no sideway forces act on the rack. But, frankly, I would not want to have the rack take up much force during milling if it can be at all avoided as it has structural function - if the bottom clamp is opened, the rack takes up the considerable weight of the column and the head...
I'll see if I can get photos of the clamping mechanism, but it's just a bolt with a handle that compresses the slotted base around the column.
--- Quote from: Arbalist on December 27, 2013, 05:11:11 AM ---It may be worth contacting this guy as he's done a lot of mods on his.
http://www.juergenschwelm.de/
He seems to speak English? so hopefully conversing with him should not be a problem.
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It's no problem, especially as I'm a native German speaker as well - in fact we're chatting regularly in a German forum. ;) He did indeed do several very nice improvements to his mill, but has since sold it for a larger one.
--- Quote ---I've not seen such a lightweight version of a mill drill like this before with no fine down feed. They seem to be popular in Germany though and folks are making some good stuff on them so your problem must be solvable! Please let us know how you get on.
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Yes, it is an extremely low-cost mill/drill. Out of the factory, it can hardly be used for milling since it comes with a very thin-walled column (like 3mm or 1/8" wall thickness) - usually the first thing you do is to replace it by a solid column. And it has absolutely no "comfort" features at all; even all of the scales are unusuable because they're just some bolted-on metall strips; the chinese do not even bother with lining them up correctly. ;) But some people like to improve the machine - it costs almost nothing (hence, no risk of damaging an expensive tool) and you learn the basics of machining the hard way, if you're that inclined. The fine down feed is a popular addition, as well as DRO, fluid cooling, 3-phase motor etc., some people even pour the base with epoxy cement for additional weight...
I guess that any round-column mill/drill is facing the problem I'm trying to solve here, so I was hoping there is a "standard" solution. But extensive searching did not turn up anything so far; I guess people are rather tending to get a larger mill without the round column, and using this only as a drill.
Swarfing:
On one of those sites i got a better view of the base. If it was my machine i would sink some more holes in that rack to secure it better to the column. You don't need to use massive screws, don't be afraid to drill through the teeth. then just above the riser handle in the column support casting sink and tap a hole up against (side on) the rack. make this the biggest you can get away with and use a brass caphead or grub screw to act as jib keeping it from turning. then from the drill another smaller tapped hole to fit a small grub screw to lock the brass one in place. i hope that all makes sense.
Jonny:
Its a generic RF25 similar to many other branded ones sold by Chester, Warco, Machine Mart, Sealey and so on.
Just got rid of mine purely due to lack of space and not used for last 9 years, it was one accurate machine with limitations.
Even milling 4" x 2" aluminium 26" long sticking out a Chinese cheap vice by 11" the head never twisted the vice back broke out.
Don't bother pinning the rack its useful way of increasing the travel from 14" in X axis.
I used to leave an 1/2" drive socket and ratchet by the side to tighten the head tight. If the tubes rotating in the bolt on base could try drilling and tapping say M8 through casting in to the tube. Is the solid replacement undersize? If so probably the problem also could try some bearing retainer Locktite.
BillTodd:
Have a lookat this triangular gib key (scroll down the page) www.lathes.co.uk/metalmaster/
Arbalist:
--- Quote from: Jonny on December 27, 2013, 07:52:27 PM ---Its a generic RF25 similar to many other branded ones sold by Chester, Warco, Machine Mart, Sealey and so on
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Take another look at the picture, it's not the same as a RF25. The head stays clamped to the column on CrazyModder's HBM16 and both are raised and lowered together by the crank on the base. If he were to bolt the column to the base as suggested he wouldn't be able to raise or lower the head with the crank!
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