Author Topic: Building a milling machine  (Read 74267 times)

Offline Pete W.

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Re: Building a milling machine
« Reply #75 on: May 16, 2014, 03:53:12 PM »
Hi there, Norman,

I think someone has already suggested this (wasn't it Andrew?) but just filling with sand would probably be a good method of damping (vibration damping, that is!).

Back in the 1060s, when I first got interested in Hi-Fi, some enthusiasts would build loudspeaker enclosures with double plywood walls and fill the intermediate space with DRY sand.  This made the cabinet acoustically dead because any sound (=vibration) energy that tried to flex the cabinet walls would be robbed of its energy by the friction between the individual sand grains.

It really does need to be dry sand - there were tales of blokes wives arriving home unexpectedly and finding baking dishes of sand 'cooking' in the oven!  The sand would also need to be first washed to remove any salt - that would attract moisture from the atmosphere and cause corrosion.

It would have the advantage that if it didn't work, it would be easy to remove to make room for something else.  Of course, you'll have to block up all of the holes in your frame except for the very top one.  Over time, the vibration from the machine would make the sand compact and settle so you'd probably need to top up the filling after a while. 
Best regards,

Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Offline NormanV

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Re: Building a milling machine
« Reply #76 on: May 16, 2014, 05:39:56 PM »
Hi Pete, you're old   "Back in the 1060s"

Sand would be a good idea, certainly cheaper than lead.

 




 



Offline Pete W.

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Re: Building a milling machine
« Reply #77 on: May 17, 2014, 03:59:10 AM »
Hi Pete, you're old   "Back in the 1060s"
SNIP

Now, now, Norman, you mustn't be pedantic!  I was only one key out!   :D   :D   :D 

   :offtopic:  Actually, I was born a couple of weeks before the Hindenberg disaster and a few weeks before King George VI coronation.
                   That doesn't count as 'old', it counts as 'mature and wise'.  Sort of more Stradivarius than Stratocaster!   :lol:   :lol:   :lol:     
Best regards,

Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Online awemawson

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Re: Building a milling machine
« Reply #78 on: May 17, 2014, 12:54:17 PM »
Ah yes but old age is a hell of a price to pay for being mature and wise  :lol:
Andrew Mawson
East Sussex

Offline NormanV

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Re: Building a milling machine
« Reply #79 on: May 17, 2014, 01:11:34 PM »
We just have to go with what we have.

Offline NormanV

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Re: Building a milling machine
« Reply #80 on: May 28, 2014, 05:31:29 AM »
I've done a bit more today. I had to wait for a period without rain which was rather frustrating.
Today I cast a part for mounting the pulleys for the drive. It is a lot lighter than most of the other parts I have cast for this machine. It is only 10mm thick.
It was a bit more complicated to mould than the previous parts I have made and I was pleased how my way around it worked out.

Offline NormanV

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Re: Building a milling machine
« Reply #81 on: May 28, 2014, 05:37:09 AM »
I made the pattern in two parts, the main part being the item itself and then the separate part that fits under the main part to fill the awkward cavity underneath. I moulded it with it standing upright on the mould board and when I had rolled it over I removed the filler piece and completed packing the sand in. I rolled it back to open it leaving the cavity filling sand on the base. The sand broke away a little at the base but that is unimportant as it can be trimmed off when I tidy up the casting.

Online awemawson

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Re: Building a milling machine
« Reply #82 on: May 28, 2014, 01:04:00 PM »
Nothing there that a bit of fetling won't sort out  :thumbup:
Andrew Mawson
East Sussex

Offline NormanV

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Re: Building a milling machine
« Reply #83 on: May 28, 2014, 03:45:15 PM »
Buoyed up by my success this morning I thought that I would do some more casting this evening even though the weather was looking a bit dodgy. I tried to be clever and cast three items in one pour. I know(?) that I cut gates between all three patterns but when I poured it seemed as if I hadn't. I got two of the castings OK but with a lot of flashing around the edges.
That will teach me not to try to rush and to beat the weather!

Offline vtsteam

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Re: Building a milling machine
« Reply #84 on: May 28, 2014, 03:47:49 PM »
Nice work Norman. Kinda hard to stop casting when you're on a roll!   We need parts, parts..... :dremel:
I love it when a Plan B comes together!
Steve
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Offline NormanV

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Re: Building a milling machine
« Reply #85 on: May 29, 2014, 03:05:11 PM »
I need some advice, I hope that someone can help. I intend taking the drive belt to the spindle on this machine above the horizontal tube that carries the head and motor. The head can be adjusted vertically, it does not have a quill as in a pillar drill but moves on a vee slide.
What I was proposing to do is mount a fixed pulley at the top of the spindle and the belt will be driven from an idler pulley mounted on a splined shaft. Do you think that the idler pulley will follow the pulley on the main spindle and automatically align itself?
Here is a sketch showing what I wish to achieve, any comments would be appreciated.
Norman

Offline Manxmodder

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Re: Building a milling machine
« Reply #86 on: May 29, 2014, 11:34:15 PM »
Hi Norm, looking at your drawing it may work if the pulley sheaves are a fair bit larger in diameter than the belt track diameter,otherwise I think it may try to shed the belt of the edge of the pulleys as they get momentarily misaligned.

Maybe you could rig up a rigid arm from the top of the head and extending to the pulley on the splined power  shaft.
 On the end of the arm nearest the splined pulley you could have a guide fork arrangement with a couple of bronze thrust slippers bearing on the top and bottom bosses of the spline pulley,this should keep the 2 pulleys in better alignment with each other rather than just relying on the belt....OZ.
Helixes aren't always downward spirals,sometimes they're screwed up

Offline Arbalist

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Re: Building a milling machine
« Reply #87 on: May 30, 2014, 05:09:03 AM »
Gosh Norman, you must have quite a stockpile of scrap alloy for all these parts!  :D

Online awemawson

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Re: Building a milling machine
« Reply #88 on: May 30, 2014, 07:11:16 AM »
Gosh Norman, you must have quite a stockpile of scrap alloy for all these parts!  :D

... all those cars up on piles of bricks in the supermarket car park ....  :lol:
Andrew Mawson
East Sussex

Offline NormanV

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Re: Building a milling machine
« Reply #89 on: May 30, 2014, 08:14:25 AM »
Oz, I had considered that idea but I haven't yet worked out a way to mount it on the head. I didn't design it with such a thing in mind and I don't really want to make a complete new one as there is a lot of work in the one I made.
Arbalist and Andrew, I was very law abiding and bought approx. 60kg of aluminium from a local scrap yard. It cost me 80p/kilo which is quite dear but at least it was clean and stripped of all ferrous parts. I am down to 10kg so may need to go for some more soon.

Offline PekkaNF

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Re: Building a milling machine
« Reply #90 on: May 30, 2014, 12:26:17 PM »
What is the big idea of putting the parts other way out normal order? I sort of get but then again - I don't get it.

Something like this:
http://www.lathes.co.uk/elliott%20mini%20jig/img8.jpg

I think that the Eliot mini jig borer is a beauty and I have collected courage to start planning of building something like it, because original ones are buffed to death and/or silly money.

Pekka

Offline NormanV

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Re: Building a milling machine
« Reply #91 on: May 30, 2014, 01:01:14 PM »
The "big idea" for doing a different way round is because I have used a milling spindle for the main shaft and I cannot see how to fit a splined shaft to it and the mount for the pulley without having to remake the whole head.
Yes, I should have planned it in advance but I didn't.

Offline tom osselton

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Re: Building a milling machine
« Reply #92 on: May 30, 2014, 02:53:24 PM »
It's a dollar a pound out here for scrap aluminum I bought about 40 pounds last year to make some ingots.

Offline kayzed1

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Re: Building a milling machine
« Reply #93 on: May 30, 2014, 03:59:41 PM »
What about a spring fither side of the pulley.
 Lyn.

Offline NormanV

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Re: Building a milling machine
« Reply #94 on: May 30, 2014, 05:47:26 PM »
Lucky you Tom, that's half the price I had to pay and I believe that it has gone up since I bought my scrap.
Lyn, that's something I hadn't thought of. I can see the value of a spring underneath the pulley to counteract gravity.

Offline PekkaNF

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Re: Building a milling machine
« Reply #95 on: May 31, 2014, 06:42:01 AM »
The "big idea" for doing a different way round is because I have used a milling spindle for the main shaft and I cannot see how to fit a splined shaft to it and the mount for the pulley without having to remake the whole head.
Yes, I should have planned it in advance but I didn't.

OK. I get it. I think (not sure, but I should consult my friend) that this construction might have a problem trough a belt tension putting strain on splined shaft. Also this would have a tendency to stick the pulley onto splined shaft. I think that the both problems would trivialize, if you could mount an arm to drilling head and use a bearing on the moving v-belt pulley to retain the pulley and absorb the belt tension. Probably deep grove ball bearings with pretty big clearance should be good for it. Or is there very minimal space for a arm?

I hope I don't approach this at obtuse angle, it is not my intention. I like to put bearing as close to load vector as I can, because my mechanical engineering skils don't amount much to go boldly where no-one dares.

Pekka


Offline NormanV

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Re: Building a milling machine
« Reply #96 on: May 31, 2014, 12:27:45 PM »
Pekka, the point you make about belt tension "sticking" the pulley onto the splined shaft is something that I hadn't thought about. I think that this could be a real stumbling block with my idea.
It would not be possible to mount an arm between the two shafts as the vee slide is in the way, I will have to use 100mm pulleys to enable the belt to pass either side of this.
I think that I will have to revisit the normal way of doing things. I would have to rely on the torsional strength of a 10mm thread to make it work, I will look into it more closely.
Thank you for your input, I was irritated by what I perceived as sarcasm in your original response but now realise that you were trying to help. Thank you.

Offline PekkaNF

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Re: Building a milling machine
« Reply #97 on: May 31, 2014, 03:59:58 PM »
I'm really sorry about irritation I caused, English is not my first language and I have tendency to use wrong wording even when my intention is help.

One more thought....I'm mot sure how much you have space there, but how about using the head design as it is and put poly-v belt on it (easy on draw bolt and such). And offset a jack shaft that is this splined shaft. Would that allow you to move the belt out of way?

Pekka


Offline hanermo

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Re: Building a milling machine
« Reply #98 on: June 01, 2014, 01:49:00 PM »
I made a very rigid lathe bench for my little 7x lathe, filled with concrete.

I had no shrinkage.

Bench is 120 mm high mild steel, 12 mm thick, in a welded box, with crossed 15 mm rebar in center, welded to each other, 3 each of x and y crossing, in the center.
I put a 200-500 kg preload in the box, by heating the rebar with propane, before welding the last end pieces in.
Steel about 50 kg, total mass about 150 kg.

Results about 95%.
Works extremely well.

A bigger 8x lathe would have been better.
Cost about 250 in materials, in Spain, 2005 or so.


Offline vtsteam

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Re: Building a milling machine
« Reply #99 on: June 01, 2014, 07:04:08 PM »
That was steel with concrete, this is aluminum-ium, um light alloy.
Not alkali friendly.
I love it when a Plan B comes together!
Steve
www.sredmond.com