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    Default Workholding Help/Ideas, Willing to Pay

    Hello and thank you for reading.

    I have a Pocket NC mill (Pocket NC) and looking for a more secure/accurate way to hold bar stock. The trouble is most vises currently available appear to fit a full sized mill which makes me think something custom will have to be made. I have attached photos of the table setup, the vise that comes with the machine and available mounting points. The machine is 5 axis and as such, the table can rotate. I am machining brass and steel at the moment. Since a custom application may be necessary, I'd be willing to discuss compensation.

    Thank you again for any ideas and help.
    Attached Thumbnails Attached Thumbnails table.jpg   table2.jpg   20190722_094031.jpg   20190722_094422.jpg  

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    First thing off the top of my head for something that small would be a toolmakers vice. They can be had for a decent price.

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    Is this bar stock to run vertically through the hole in the center of the table, (you are going to machine the end) or lay parallel to it (you want to machine features "down the side")?

    If the first, you could look into making/mounting a collet chuck of some sort - so the tail of the chuck hangs down into the hole in your table, the nose points up towards the sphere the spindle can reach. You'd have to search something like the hardinge workholding catalog for collet types that will fit in that space. Workholding collets (5c for example though that's surely too large) come in round, square, hex, etc.

    Tool holding collets (say ER11) can be small, and hold very small things - but the collets are normally only for round stock.

    For horizontal work, I second CAMasochisms suggestion.

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    Quote Originally Posted by CAMasochism View Post
    First thing off the top of my head for something that small would be a toolmakers vice. They can be had for a decent price.
    Thanks. I did see some small toolmakers vices, but didn't know how to go about securing them to the table. I suppose some custom brackets of some kind.

    Quote Originally Posted by bryan_machine View Post
    Is this bar stock to run vertically through the hole in the center of the table, (you are going to machine the end) or lay parallel to it (you want to machine features "down the side")?

    If the first, you could look into making/mounting a collet chuck of some sort - so the tail of the chuck hangs down into the hole in your table, the nose points up towards the sphere the spindle can reach. You'd have to search something like the hardinge workholding catalog for collet types that will fit in that space. Workholding collets (5c for example though that's surely too large) come in round, square, hex, etc.

    Tool holding collets (say ER11) can be small, and hold very small things - but the collets are normally only for round stock.

    For horizontal work, I second CAMasochisms suggestion.
    Yes, the bar stock will be running vertically through the hole. Thank you for this idea and I will look more into it. The ER40 collet fits the hole and I was trying to stay away from round stock as I'd have to rough out more material. I was hoping for a vise so that I can change the dimensions of the stock. And to the last idea, I'm not sure how to secure the vise to the table but will try to think of some ideas.

    Thank you for these ideas.

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    Quote Originally Posted by tayamo1 View Post
    Thanks. I did see some small toolmakers vices, but didn't know how to go about securing them to the table. I suppose some custom brackets of some kind.
    I would make a sub-plate that would mount to the bolt holes already on the table. From there you would just tap some holes for clamps to hold the vice in place.

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    My experience with toolmakers vises for milling has always ended up with the part moving. They are for grinding, not milling.

    What is the diameter of the part in the cad images?

    With the right vise, you could lay it on its side to hold the stock.

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    Quote Originally Posted by DavidScott View Post
    My experience with toolmakers vises for milling has always ended up with the part moving. They are for grinding, not milling.

    What is the diameter of the part in the cad images?

    With the right vise, you could lay it on its side to hold the stock.

    I think his machine has a max tool diameter of like 4 or 5mm... He's not gonna be doing much hogging.

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    @tayamo1 - "Yes, the bar stock will be running vertically through the hole. Thank you for this idea and I will look more into it. The ER40 collet fits the hole and I was trying to stay away from round stock as I'd have to rough out more material"

    Right, so first, the issue is what collet *chuck* fits in the hole - you need the chuck to secure the collet. (Is there some kind of ER40 adapter for it? That would be a fine way to start. But just having an ER40 collet fit in the hole isn't quite enough.)

    Second, the reason to look into 3c or 5c is that they support standard collets for square and hex as well as round.

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    Quote Originally Posted by TeachMePlease View Post
    I think his machine has a max tool diameter of like 4 or 5mm... He's not gonna be doing much hogging.
    I have tried using a 3" toolmakers vise two times for ultra light milling work. It was on a Bridgeport when I was making plastic injection molds so all the machining time was in the setup, how fast I cut metal didn't really matter. I machined as light as possible but the parts still moved on me to the point I was not able to do the job with the setup. This is why I say that in my experience toolmakers vises don't work for milling. And yes I had the clamp screw extended as much as possible so it was pulling the jaw towards the fixed jaw and not just towards the vise bed. I tried to make it work.

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    Another thought. A toolmakers vise on its side with a C clamp or Kant Twist helping clamp the part. If I'm FOS then you will figure out the vise alone is all you need.

    How big are your parts?

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    The 'chuck' is designed for ER40 collets, as shown here: ER40 Collet
    – Pocket NC


    I would think if there's a reason to need less roughing (rather than just wanting it), that it strongly suggests the best choice is to move up to a larger machine, rather than trying to do production on a machine with poor tolerances by design and very little horsepower.

    If the OEM vise works but just isn't consistent enough, add some dowel pins for tight tolerance (maybe recreate it without the hole pattern and do that). That said, I think the manufacturer only specs something like 0.002" runout and repeatability on the axes, so my guess is the chuck isn't really the issue there.

    I'd be interested in taking a whack at a model of something if you're willing to share the Fusion model you've made. I don't see any publication of the hole pattern elsewhere.

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    How big is the bore? Making a custom collet chuck isn't much of a project if you have a manual lathe.

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    Quote Originally Posted by DavidScott View Post
    My experience with toolmakers vises for milling has always ended up with the part moving. They are for grinding, not milling.

    What is the diameter of the part in the cad images?
    It's 53mm or 2.08661 inch inside diameter and 89.93mm or 3.54 inch outside diameter.


    Quote Originally Posted by TeachMePlease View Post
    I think his machine has a max tool diameter of like 4 or 5mm... He's not gonna be doing much hogging.
    Correct, I can do 3mm, 3,125mm or 4mm shank.

    Quote Originally Posted by bryan_machine View Post
    Right, so first, the issue is what collet *chuck* fits in the hole - you need the chuck to secure the collet. (Is there some kind of ER40 adapter for it? That would be a fine way to start. But just having an ER40 collet fit in the hole isn't quite enough.)
    .
    Yes, Pocket NC makes an adapter. There's an instagram individual named Ed Kramer (ekramer3) who does what I think you have in mind. He's holding a round bar of stock with the ER collet and fixes a 4 jaw chuck to the round stock. I dont have the means to thread the round stock. I can visit a machine shop but just developing a game plan right now.

    Quote Originally Posted by DavidScott View Post
    Another thought. A toolmakers vise on its side with a C clamp or Kant Twist helping clamp the part. If I'm FOS then you will figure out the vise alone is all you need.

    How big are your parts?
    Pretty small parts - the biggest would be around 30mm x 3mm and smaller.

    Quote Originally Posted by Pariel View Post
    The 'chuck' is designed for ER40 collets, as shown here: ER40 Collet
    – Pocket NC


    I would think if there's a reason to need less roughing (rather than just wanting it), that it strongly suggests the best choice is to move up to a larger machine, rather than trying to do production on a machine with poor tolerances by design and very little horsepower.

    If the OEM vise works but just isn't consistent enough, add some dowel pins for tight tolerance (maybe recreate it without the hole pattern and do that). That said, I think the manufacturer only specs something like 0.002" runout and repeatability on the axes, so my guess is the chuck isn't really the issue there.

    I'd be interested in taking a whack at a model of something if you're willing to share the Fusion model you've made. I don't see any publication of the hole pattern elsewhere.

    I would love a bigger machine, however, that appeared to be several thousand $$ more. Additionally, this Pocket NC can fit inside a house and I dont have to worry about moving a 500lb machine 5 axis in a larger machine also would have added significant cost. I've been getting great repeatable tolerances (within .05 millimeter) when I take my time and dial everything in. My issue is that I need to rotate the part 180 degrees to access the backside. When I currently do this, since the part is on the edge of the table, the part is now too far from the spindle and I run out of Z axis (See the photos of how the vise sits towards one side of the table). So I need the part in the middle of the table - I'm outgrowing the OEM vice.

    I'm willing to share the Fusion model, how do I contact you? Through PM?

    Thank you for your time everyone!

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    How thick is the table and how far out the back can something stick out of it? A 5c collet chuck would be a lot handier than the ER40 if there is room.

    The total length of a 5c collet is 3.375". Stick as much out the back as you can and the rest can be proud of the table.

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    I would think you'd want the smallest 5 axis vise you could find. The dovetail jaws work w/ or w/o a mating dovetail, obviously they work better with one. You could also have an import toolmakers vise ground to have a dovetail. Without the means to make / modify your own tooling is a problem that will likely only be solved by throwing money at it, at which point the Kurt vise below is a pretty good deal.

    DoveLock™ DT20 5-Axis Dovetail Vise | Dovetail Workholding

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    Maybe put a more exact location (or PM anyone interested) and offer to buy them a case of beer to come look at your setup and brainstorm some ideas. Be prepared to pay $50-100/hr plus mat'l for machine work if you want something custom made.

    I would look into these -
    https://www.mscdirect.com/industrial...ptor-vise.html

    They are spendy, but low profile and compact.

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    Quote Originally Posted by DavidScott View Post
    How thick is the table and how far out the back can something stick out of it? A 5c collet chuck would be a lot handier than the ER40 if there is room.

    The total length of a 5c collet is 3.375". Stick as much out the back as you can and the rest can be proud of the table.
    The table is 50.5mm or 1.9 inches tall. There is about 19mm or 0.74 inch room below the table for stock/equipment to hang.

    Quote Originally Posted by Nmbmxer View Post
    I would think you'd want the smallest 5 axis vise you could find. The dovetail jaws work w/ or w/o a mating dovetail, obviously they work better with one. You could also have an import toolmakers vise ground to have a dovetail. Without the means to make / modify your own tooling is a problem that will likely only be solved by throwing money at it, at which point the Kurt vise below is a pretty good deal.

    DoveLock™ DT20 5-Axis Dovetail Vise | Dovetail Workholding
    What's funny is I called Kurt today and they didnt even mention this. Thanks for pointing it out.

    Quote Originally Posted by Mike1974 View Post
    Maybe put a more exact location (or PM anyone interested) and offer to buy them a case of beer to come look at your setup and brainstorm some ideas. Be prepared to pay $50-100/hr plus mat'l for machine work if you want something custom made.

    I would look into these -
    https://www.mscdirect.com/industrial...ptor-vise.html

    They are spendy, but low profile and compact.
    Thanks for sharing these.




    I'm very grateful for a friend who shared this idea, take a Sherline Chuck here:

    Sherline self-centering 4-jaw ER16 chuck, part #1078 -
    3.1″ 4-Jaw Chuck – ER-16 – Sherline Products

    and mount it on a stick:

    Shars 3/4" Straight Shank Toolholder with ER16 Collet Chuck, part
    #202-1423 -
    ER16 ER Collet Chuck Tool Holder with 3/4" Straight Shank

    and hold it in the table with the ER collet here:

    Pocket NC ER40 Collet Fixture with 3/4" ER40 Collet -
    ER40 Fixture
    – Pocket NC

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    Hi tayamo1:
    You DON'T want to have a 4 jaw self centering chuck unless your stock is perfectly (or almost perfectly) square.
    If it's out even 50 microns it will effectively only be a 2 jaw chuck, and the part will rattle in the chuck.
    You do not appear to have any means to make it square, so I would not go that route.
    Instead, buy a Sherline 4 jaw INDEPENDENT chuck so you can adjust each jaw individually and clamp even irregular parts very securely.

    Next, avoid if you can, a chuck on an arbor, in another chuck...it will become hopelessly floppy.
    Instead, drill and counterbore a bolt pattern right through the chuck body and bolt the chuck directly to the mill table.
    It won't harm the chuck, not even cosmetically if you machine it properly so it looks like it was done in a civilized country and if you avoid the tracks for the jaws.
    2 bolts will be plenty, but if you can find room to place 3 or 4, no harm in that either.

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining

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    I mill small inserts for injection molds using a toolmakers vise all the time with no issues.

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    Quote Originally Posted by implmex View Post
    Hi tayamo1:
    You DON'T want to have a 4 jaw self centering chuck unless your stock is perfectly (or almost perfectly) square.
    If it's out even 50 microns it will effectively only be a 2 jaw chuck, and the part will rattle in the chuck.
    You do not appear to have any means to make it square, so I would not go that route.
    Instead, buy a Sherline 4 jaw INDEPENDENT chuck so you can adjust each jaw individually and clamp even irregular parts very securely.

    Next, avoid if you can, a chuck on an arbor, in another chuck...it will become hopelessly floppy.
    Instead, drill and counterbore a bolt pattern right through the chuck body and bolt the chuck directly to the mill table.
    It won't harm the chuck, not even cosmetically if you machine it properly so it looks like it was done in a civilized country and if you avoid the tracks for the jaws.
    2 bolts will be plenty, but if you can find room to place 3 or 4, no harm in that either.

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining

    "...machine it properly so it looks like it was done in a civilized country"

    Thank you for the warning on the self centering jaws.


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