Magnetic mill vice

Just thinking aloud, would it be a good idea to convert a door maglock for use as a magnetic milling vice?

**LINK**

I have seen some maglocks with holding power of about 500kg, for thin or irregular shaped work pieces should be more than enough clamping force... To be honest I'm tempted but before doing something silly I would appreciate your thoughts

The lifting power of Bux lifting magnets is very dependant on the thickness of the material it is being used to lift. Thin materials reduce the load that can be lifted. I suspect a door maglock may have similar issues. This is why magnetic tables for machine tools are usually multi-pole. Is the maglock multi-pole? What is the plate used with maglocks like?

Martin C

Hi Chris,

From a sufficient number of years of toolroom experience with surface grinders, both chucks with either permanent magnets or DC electromagnetic, I would expect that the rapid, intermittent cutting forces from millng tools, could slowly dislodge/move a work-piece out of alignment. Clearly, this would require some positive means to stop this in the X and Y directions.

I would also suggest that you'll need a de-magnetiser, to reduce the annoyance of (carbon steel) work-pieces remaining magnetic. On that score too would be the collection (and removal) of swarf around the 'vice'.

Using a dial indicator for 'clocking up' near such a vice is also likely to introduce issue with immediate/residual magnetism.

I'm sure this thread will attract other views.

Good luck,

Sam

Could be handy on the base of a pillar drill instead of a vice

I got one for 15 quid from a well known site, worth a shot methinks

Oh, I forgot!

There's the issue of your milling cutters grabbing swarf and needing to be 'demagged'.

You will also find that it disrupts the action of a wobbler when trying to find an edge. And the wobbler, being made of carbon steel, will get magnetised and need demagging if ever to work properly again.

I think it's a single pole DC electromagnet magnet, the plate is 16mm thick and on that plate it gives a hold down force of 550kg.

It also depends what machining operation is being carried out I think, say, you will not use it to hold a workpiece you're flycutting, but maybe if using a small endmill the forces would be lower?

I did some work on machining thin parts and in the end abandoned magnetic and found that a vacume plate was superior as you could hold non ferus parts as well. All you had to do was contain the vacume with an o-ring in the criss cross track in the base plate and make sure that the spare holes in the vacume holes were fiĺled with a grub screw. Look at Thame workholding which we used.

David

I have not seen a commercial mag vice for a mill (not that there isnt one because I haven't seen one). I suspect that the holding power is not enough for general milling but there may be very specific circumstances where a light cut on some jobs would be OK . They seem to be ok for surface grinding but the forces involved are very different. You would be limited to steel so all the other materials we use would need conventional holding systems that are also good for steel. A scenario I imagine a mag chuck would work would be CNC engraving on a plate of a reasonable thickness and size.

Mike

Magnetic drills have been around for a long time, but one would still take precautions if they were used on vertical surfaces!

Surface grinders are one thing and milling machines are another. Holding force quoted will be the maximum rating - thick, flat and over the whole magnet area - and not brass, aluminium or even most stainless steels. Seems a limited piece of kit to me, even in its optimal form, without trying something not designed for that use.

Magnetic chucks on lathes are not common but obviously have their uses, too.

Let us know how you get on, or perhaps there are some out here that already use the normal surface grider type magnets on their mills. I have one, but have never even contemplated fitting it to a mill table. If they don’t, I wonder why!

Edited to add that the Eclipse range decidedly point one to their “supermill” product.  The blurb says 10 tons holding force per square foot for those.

Edited By not done it yet on 20/06/2018 08:28:52

I bought a magnetic vice some years ago from a well known supplier and found it to be totally useless for milling.

I dont even bother with it for drilling,I just dumped it on to a shelf somewhere.

Maybe the real industrial vises are OK,but not the ones we are offered.

Hold down force may be 500Kg but you need to know the shear force don't you? As has been mensioned you are going to need some positive sto[s in the X and Y anyhow.

Does anyone make a mag chuck for milling commercially? Could be a clue there?

regards Martin

Edited By Nick Hughes on 20/06/2018 09:33:25

Not in a production or small scale production based business Nick they would be bankrupt by the time its removed such a small amount in a very very long time.
Usually videos like that are at max speed for the job and tool in question, first part is just simple job rotation force equal!
2nd part cannot understand any company using that, current crop of good tooling would do that 30 times quicker no joke have a look at Seco, Kenametal, Ceratizit etc.

Surface grinders granted have been used for decades to good effect we used them on all the Snows and Churchills. Difference is taking minimal cuts no jolting or interupted cuts.

Just came across this https://www.youtube.com/watch?v=zYJfVQHF2Tk
Crow bar yes but no real effort required to dislodge.
Gets worse the smaller the part held the less force.

Other problem the magnets and or contact strip needs full contact over that area for max effect, not to mention the straightness and constant clocking up dependant where jobs put.

The term ELECTROmagnetic is surely a clue, Nick Hughes, to the fact that a permanent magnet is not considered man enough. And note the term 'precision milling', which implies (to me at least) the removal of small amounts of metal but accurately. The picture does show the workpiece fitting the magnetic area almost exactly - that too might be a clue.

Regards, Tim

Electro magnet, a bit like the maglock the OP was referring to!

The Turbomill Chuck obviously has a market, otherwise it would not be in production, PLUS I only posted the clip,

in response to earlier posts.

Speculation as to their use/usefulness I'll leave to others.

Nick.

Here's a bit more Chris,

Another issue came to mind, particularly with what can happen when machining BDMS (bright drawn mild steel). Skimming a surface of a rectangular bar of BDMS can release built in stress sufficient to cause the bar to bend. Insufficient hold down force would allow the steel to lift towards the cutter.

That aside, and since we are talking about an electromagnet, I can’t resist describing the situation in the tool room back in the early 50’s. There were three surface grinders. The chucks on two were electromagnetic, and the third had a chuck with permanent magnets.

The shop’s workhorse surface grinder (with an electromagnetic chuck) was driven from a counter-shaft running the length of the shop. A 10 hp electric motor at one end of the shaft provided the power. Imagine, in the middle of grinding a workpiece, the urgency when there is a power cut. It happened on more than one occasion.

One chap was grinding a line of steel inserts secured to the chuck when the power went off. The chuck let go, and the still spinning grinding wheel propelled the line of inserts against machine’s end guard like bullets from an automatic machine gun.

More food for thought eh?

Sam

Hi Sam, yes that is one of my concerns if I had to consider going that way (which after reading through the replies on here is very unlikely!) But if I had to go ahead, I would for sure connect the magnet to a UPS or a battery, although I would not be much worried about my wm18 with a small endmill on it, ramps down pretty quick when turned off.

I worked on electro magnetic chucks on grinders and they are magnetised electrically and then have to be de-magnetised electrically. They will stay magnetised if there is a power cut etc and there is a relay preventing start when not magnetised.

David

Do the gates become unlocked in the event of a power cut? If so, they would not be such a good security device!