machining rough castings

[Pakrattuk]

Hi, not posted before (apart from my joining post) but hope you wont hold that against me. Looking for some advice (maybe ad -vice) on how to hold some rough castings for swan neck clamps to try and machine them reasonably square and somewhat similar to each other. Have flycut the bottom surface to give me some sort of datum to work off of but would like to get the opposite face parallel to the bottom and also the clamping face parallel to the other two faces. The rest doesn't need to be sqaure to anything as far as I can see but think these three faces should be machined for some sort of accurate clamping. I may be wrong on all counts and they don't need machined at all but any advice gratefully accepted. Think I may have attatched a photo of said castings
TIA
Pakrattuk

[CrazyModder]

I would simply clamp them with a screw at one side of the slot, machine down the accessible parts, then add another screw at the other side of the slot (before removing the first screw). As the part should not move at any point and you already have a reference surface on the bottom, there should be no noticable step between the operations.

[mexican jon]

I'd machine them on a magnetic chuck 

[Pakrattuk]

Thanks for the replies, might try the holding down with a screw method.The magnetic chuck idea  - if only - off for a look for one on ebay now

Pakrattuk

[PekkaNF]

I'd machine them on a magnetic chuck 

Would these stay on magnetic chuck on their own?

I got four like that. Put them on vise. It's not necessary to mill the sides and definately you don't want to make them too thin, but I had a vise and wanted to get four done fast.

1) Sides: put a thin plate trough the slot to align them, skimmed the top flat and then put them deeper in vise, skimmed side on top of a parallel. Then trued both sides.

2) Bottom: Both sides are parallel, time to tinker bottom straigh. I removed minimum, checked that "nose" will fine.

3) Top: bottom on top of parallel, clamped on sides in the vise. I just used this setting and milled all of them once.

4) Nose, you want this a little negative, something like -2 degrees, then you have positive grip even when clamp is level

https://www.cromwell.co.uk/images/product/IND/425/IND4251015N_1.jpg

IMHO, nose bottom machining is important, top only close to nose where washer and bot goes, and tail, where it contacts block.

Pekka

[Pakrattuk]

Cheers for the drawing, and probably right about the magnetic chuck idea - it would have been an excuse to get one though :-). I'll give it a go as you suggested, just trying to end up with something useable.
Pakrattuk

[mexican jon]

I'd machine them on a magnetic chuck 

Would these stay on magnetic chuck on their own?
Pekka

I don't see any reason why they wouldn't  I regularly grind smaller pieces on my surface grinder 

[Fergus OMore]

I think that it refers to the number of poles in magnetic chuck which varies and some will not hold small items- which unless there is bar, will shoot off. I have one which does, one which doesn't. However, the job is simpler if a vice/vise is used and the sides are made parallel by filing, with an angle grinder or even a DE grinder or belt sander.

It isn't difficult and failing all of this, why not a bit of a £1 bottle of epoxy resin on a face plate? When the job is done, heat up and knock off.

[PekkaNF]

I'd machine them on a magnetic chuck 

Would these stay on magnetic chuck on their own?
Pekka

I don't see any reason why they wouldn't  I regularly grind smaller pieces on my surface grinder 

Castings are often rough and awkward shape and surface grinder is different animal than milling machine, isn't it? I would be too chiken to try. Maybe you could get away if you butt it against a parallel or something that has more "grip" on magnetic table/chuck AND a milling cutter that does not lift the piece?

Rough pieces can be held in vice if some aluminimum/copper plate/angle/rod packing is used.

I was assuming that there is milling machine, because "flycut" on opening post.

[Pakrattuk]

You were right to assume milling machine - thanks for the suggestions

[mexican jon]

I'd machine them on a magnetic chuck 

Would these stay on magnetic chuck on their own?
Pekka

I don't see any reason why they wouldn't  I regularly grind smaller pieces on my surface grinder 

Castings are often rough and awkward shape and surface grinder is different animal than milling machine, isn't it? I would be too chiken to try. Maybe you could get away if you butt it against a parallel or something that has more "grip" on magnetic table/chuck AND a milling cutter that does not lift the piece?

Rough pieces can be held in vice if some aluminimum/copper plate/angle/rod packing is used.

I was assuming that there is milling machine, because "flycut" on opening post.

I'd agree with most of the comments  But as Pakrattuk had said that the bottom had already been fly cut, and working on the average size of a clamp I personally would clamp them on a magnetic chuck  as there will be a resonably sized flat surface for the chuck to hold  saying that I could be wrong  I will give it a try when i get home just to see if it does work 

[PekkaNF]

.....
I'd agree with most of the comments  But as Pakrattuk had said that the bottom had already been fly cut, and working on the average size of a clamp I personally would clamp them on a magnetic chuck  as there will be a resonably sized flat surface for the chuck to hold  saying that I could be wrong  I will give it a try when i get home just to see if it does work 

Good. This is interesting. Any chance of a picture and note about the chuck and milling cutter.

Pekka

[mexican jon]

.....
I'd agree with most of the comments  But as Pakrattuk had said that the bottom had already been fly cut, and working on the average size of a clamp I personally would clamp them on a magnetic chuck  as there will be a resonably sized flat surface for the chuck to hold  saying that I could be wrong  I will give it a try when i get home just to see if it does work 

Good. This is interesting. Any chance of a picture and note about the chuck and milling cutter.

Pekka

Yes  Once i get back from work in about 4 weeks time I'll set something up and try it  Pictures will be included of  either a machined surface or the location of said part and the distance it travelled from the mill 

[trapper]

I have a set of these clamps mine have a drilled/tapped hole in the "heel" end so you can put bolt in and adjust it with a locking nut on-as for machining.I would say the underside which locates on job would need skimming,and maybe top -so the clamping bolt has a seating for the washer-thats it really-but if you wanted to a rough jaw vice sometimes known as a "Yankee" vice is for use with rough castings or irregular shaped jobs,such as this one.I would put one in vice and skim sides-then transfer to smooth jaw vice and complete-