Shaft clamping in a V-block for milling

Hey guys, a little help required here:

We do a lot of batch production jobs which involve secondary operations on shafts held in V-blocks on a VMC. (No Turnmill for me yet !)

The Shafts range from Dia 20 upto 45 mm and length range 300-1000 mm.

One of the (rather, crude) setups is as shown in image where series of grooves are cut in shaft while being held in V-Block with help of Straps. These straps, are in turn, clamped on V-block using M12 bolts on both sides and hence secure clamping.

My Question is: What will be the better way to clamp these shafts on V-block ?
Milling operations are quite aggressive in shafts, and hence clamping has to be quite secure. Current setups waste a lot of time in clamping / declamping.

(For smaller shafts, we quite often use Lockdown vice equipped with custom V-groove cut soft jaws. Setup is very rigid then. But can't use those for longer shafts.)

its had to tell how thick your top straps are. but the setup looks good to me. I have seen people also use self centering vises on long set ups with soft jaws, and a V block on either end for alignment.

Hoss710 said:

its had to tell how thick your top straps are. but the setup looks good to me. I have seen people also use self centering vises on long set ups with soft jaws, and a V block on either end for alignment.

Click to expand...

Straps are 1" wide, 1/2" thick.
There's a lot of Z axis plunge milling, hence clamping required almost near every pocket.

Sent from my Redmi Note 4 using Tapatalk

ever seen a scope mount for a rifle?

https://www.ebay.com/i/281312038450...85634&itm=281312038450&pmt=0&noa=1&pg=2385738

(If the spacing of features allows)

Do you have any vises to clamp the shafts in vs using the V-blocks. if you have you can use 4-5 kurt vises with soft or hard jaws to hold the parts pretty secure when machining the shafts.

Vishrut said:

Hey guys, a little help required here:

My Question is: What will be the better way to clamp these shafts on V-block ?
Milling operations are quite aggressive in shafts, and hence clamping has to be quite secure. Current setups waste a lot of time in clamping / declamping.

(For smaller shafts, we quite often use Lockdown vice equipped with custom V-groove cut soft jaws. Setup is very rigid then. But can't use those for longer shafts.)

Click to expand...

Your setup looks like you are using the table slot with bars clamped either side for your part clamps. Real v-blocks keyed to the table correctly will give a better setup for abusing round things well.

I’d ditch those socket head capscrews and use studs & flange nuts. Attached is a pair of swing & slide out I use with my 6” v-blocks, shown is one clamped over a 2 3/4” bearing diameter.

For your setup you could forgo the back slot like mine and just drill a hole for the back stud, put springs under the back studs & run happily.

Good luck
Matt

I would be inclined to *think about* a scheme with some number of vises with large v-jaws in them. Said vises have fixed jaw very carefully aligned to table (and each other). They have a jaw that looks like this:
V Jaw, Hardended and Ground, 6"

How is this relevent to Vishrut's question? At least when using 1 of them (which I have done) parts go in and out quite quickly, and they are quite secure. So IF and ONLY IF you can get enough vises spaced so you can get at the features (say 3 or 4 vises for your 1 meter parts) - then I would think parts could be loaded/unloaded pretty quickly. Of course, you have to align all of the vises, and at least the Kurt factory versions of these jaws are pretty pricy.

I do a ton of shaft work.. Its not fun, but its easy money..

This morning its an 8ft, 1.25" stainless shaft that just needs to be keyed about
18" on both ends.. A simple one.

I'm going to do it exactly how I've always done it. Just drop the shaft across
3 vices.. Close vises, load program and go.. I don't even need to pick up a
fixture offset since the left corner of all my vises is stored in offsets
21,22,23, And in offset 41 42 43 is the corner with hard jaws on.

I think I'd shoot myself in the head if I ever had to do all these shafts
with v-blocks and clamps.

cyanidekid said:

https://www.ebay.com/i/281312038450...85634&itm=281312038450&pmt=0&noa=1&pg=2385738

(If the spacing of features allows)

Click to expand...

Seems vices would be long, I have less distance between adjacent pockets.

Rewt said:

ever seen a scope mount for a rifle?

Click to expand...

Would that be good when diameters keep on varying ?
I am looking for solution for diameter range 20 mm....upto 50 mm.

Shawnrs said:

Do you have any vises to clamp the shafts in vs using the V-blocks. if you have you can use 4-5 kurt vises with soft or hard jaws to hold the parts pretty secure when machining the shafts.

Click to expand...

As stated earlier, we've hundreds of these to make. Opening & closing 4-5 vices will kill a lot of time IMHO. Ofcourse, the clamping will be super rigid.

barbter said:

You could make a fixture along the lines you have, with half slots in the clamps where you have the drilled screw holes.
So you can slide the clamp into position under a headed screw (for example) and then have a centre screw in the middle of the clamp to secure the part.
This way, you only have to crack off the centre screw 1/2 turn and slide the clamp out.

Click to expand...

I would request you to elaborate a little bit more on this... Wouldn't I need to tighten (a little bit,) those headed screws? 'coz you take the clamp out every time while loading / unloading.

Can we get some more pictures please? Having a hard time getting the idea.

Google Image Result for http://d10b75yp86lc36.cloudfront.net/Monotaro3/pi/full/mono21403612-160331-02.jpg

Only one nut to tighten on each clamp. Carr Lane has a great illustration of this arrangement. Unfortunately I could not copy the image. A spring supports the strap. Once the nut is loose the clamp can be slid back or pivoted to clear the work.

Vishrut said:

As stated earlier, we've hundreds of these to make. Opening & closing 4-5 vices will kill a lot of time IMHO. Ofcourse, the clamping will be super rigid.

Click to expand...

It doesn't take that long to open up a vise and close it. I would say it take a lot less time vs the set up you showed. We machine thousands of shafts each year from long length to multiple sizes. Most of the time you only need to clamp a couple of vises depending on what you are doing. When it comes to milling flats the area you are milling is usually the vise you are clamping the most.

Vishrut said:

As stated earlier, we've hundreds of these to make. Opening & closing 4-5 vices will kill a lot of time IMHO. Ofcourse, the clamping will be super rigid.

Click to expand...

Good grief! "Hundreds" is justification enough. Multiple tens of thousands are not uncommon, either.

Invest in a proper (set of) fixtures for the tasking, then! Vee blocks are about as "general purpose" as one can get, but that's like rounding corners on millions of food-service industry table-tops with a hand-held Chinese chef's knife instead of a spindle shaper..

Bespoke clamping is "normal" in industry.

JFDI.

Semi-general-purpose vises to center rounds repeatably have also existed for hundreds of years. Perhaps thousands?

But one of MANY - Chinese made, this one - as an example:

Precise Vise For Holding Shafts & Round work - RSV-400 - Penn Tool Co., Inc

But you don't even need to leave India to find them, either. Plenty of similar goods made closer than China. Under your own roof, even - mills can do all sorts of clever things.

Use "the French approach".

Just extract the "big head" from rectal defilade - open yer eyes - and LOOK for them. Store-bought, even.

Why would you think no one else ever had this challenge - and solved it - long before you walked in the door?

It’s easier to drive a nail with a hammer but if all you have is a crescent wrench you can drive a nail with it if you want to, and the wrench IS adjustable... (YOU adjust to the v-block, after you put it in the right place)...

With v-blocks (here) the center is “0” X-axis reference and you resolve from there by changing your offset if you are working on the side of the bar (when changing bar size or the stock varies much & it needs to be that close). When set up they are completely connected to the machine tool & when you really abuse things this shows up quick.

I assumed the only thing that was bothering the OP was the time fiddling with all the clamps & capscrews over the top of the bar? In that case any strap that would swing away by just loosening one end, swing or slide out → would fit the bill as you just loosen 4 nuts per your pictured example. I wouldn’t advise big straps over a bar in the middle of a table with clamp screws in the middle though (it’ll tend to bow the table).

Is there something else that is failing in the setup? The only improvement I can imagine (if the T slot is to narrow & can’t effectively restrain the larger 1.75”dia’s from wobble or rotating) would be a dedicated v-block (long) or a set that would properly restrain the shaft from rotation with the restraint points/planes near 120°. Dilemma attached. Also attached is full view of example v-blocks shown with multi-dia shaft clamping for keyseating #6 (stub morse) driving taper (4 planes in a 3 axis machine?). It can be done single or multi-vice but resolving diameters, elevation & variable gage length from the bearing shoulder gets on your nerves really quick...



Good luck
Matt

Tichy said:

Can we get some more pictures please? Having a hard time getting the idea.

Click to expand...

Here it is...V-Block is held in position by keyway, tightened by strap clamps on table.
Shaft is clamped in V-block using multiple strap clamps which are based on v-block.

Nice !
Never thought of this.

Clamp/declamp would be pretty fast in this case I believe.