Edge Finder

[Ashish B]

Hi All


Attached herein is a part which is to be picked up...The problem is that part has a Point Contact while Pickup...

(Refer Attachment)

Generally edge finders are used for picking up part's edges, where a line contact.....

Have ever anybody picked up points in such fashion by edge finder.......

Need Help.......

[Charlie Gary]

Originally Posted by Ashish B Hi All Attached herein is a part which is to be picked up...The problem is that part has a Point Contact while Pickup... (Refer Attachment) Generally edge finders are used for picking up part's edges, where a line contact..... Have ever anybody picked up points in such fashion by edge finder....... Need Help.......

What you propose to try will be difficult to achieve because the height of the edge finder will be as critical as the size and shape of the chamfer/radius on the end of the edge finder.
How far from the back edge to the angled point? I would try for the straight side. How close do you have to get?

[wildwestpat]

Hi Ashish

Suggest you look to pick up on some other part of the shape. It will be very difficult to pick up a reliable reference on the slope you have indicated. If the object is a simple triangular section then the triangle tips are a suitable point for referencing the rest of the points on the work piece. i.e. the point indicated is so far away from the reference edge. For those with 4th axis capability rotation of the object is a practical possibility to help establishing a reference point on the object with respect to the machines axis.

Hope this helps

Regards

Pat

[Ashish B]

Originally Posted by wildwestpat Hi Ashish Suggest you look to pick up on some other part of the shape. It will be very difficult to pick up a reliable reference on the slope you have indicated. If the object is a simple triangular section then the triangle tips are a suitable point for referencing the rest of the points on the work piece. i.e. the point indicated is so far away from the reference edge. For those with 4th axis capability rotation of the object is a practical possibility to help establishing a reference point on the object with respect to the machines axis. Hope this helps Regards Pat

Hi...


I have to get over there in microns....

We have a 4th axis Parts ( around 50 ) parts which have a rework operation...
We are fighting with the orientation of the part...


Can anyone suggest me a good weapon or trick to do so.

It really takes a hard time to align the face in X Y Plane...


Still FIGHTING WITH IT.

[Charlie Gary]

Originally Posted by Ashish B Hi... I have to get over there in microns.... We have a 4th axis Parts ( around 50 ) parts which have a rework operation... We are fighting with the orientation of the part... Can anyone suggest me a good weapon or trick to do so. It really takes a hard time to align the face in X Y Plane... Still FIGHTING WITH IT.

If the parts are all the same, can you build a fixture to hold them after you locate the fixture itself? Maybe an edge finder isn't the right tool. Will a wiggler do?

[wildwestpat]

Hi Ashish

The part you are trying to relocate on your mill requires further machining operations to an accuracy that you describe as being measured in microns. 1 micron = 0.001 mm. This will be difficult no matter how you set about it. A picture or drawing of the part would help convey what you are attempting to locate. Normally parts made to this sort of accuracy are machined at one setting and have very deffinite reference edges integral with the design. Some times the reference edges are removed as the last machining operation.

I have come across the need to locate a flat surface to a high degree of accuracy and used a surface silvered mirror and a laser beam to bring the plane of the mirror and the object into parallel paths i.e. trammed in both the 'X' and 'Y' axis. However a lot more detail on the part and the machine tool would be necessary as well as the tolerances required. I fear that if you have to achieve an accuracy of a couple of microns then you will have a lot of scrap parts.

Sorry to be so gloomy

Regards

Pat

[Ashish B]

Hi...All

Well, the buidling a fixture for the part will do, but i believe in the concept why to turn to tradinational methods if any advance method is around.

Well as i narrated to you that its a 4th axis type of part, with a contour profile.

Ok....Have ever anyone heard about any such alignment instrument for aligning the part ( of 4th axis ) to the machining centre. Has anybody ever seen any such product in the market which is easy for use & which fulfilles the orientation of parts machined on 4th axis.

Specially this becomes a hectic when u need to rework any part of 4th axis.

Ash.

[Ashish B]

Hi All

Well i have attached a part model & everything is described in the attachment.

Ash

[wildwestpat]

Hi Ashish

From your 3D model it would have been best to coninue with the profile cutting of the purple plane with the 4th axis locked.

It would have been helpful if you had included some dimensions as the approach will be different depending upon the size of the part and the accuracy required. Also the surface finish of the red face and the orange in your sketch will also impact on the end resulting accuracy.

As the job has been started using the blue part as the reference you may like to consider continuing to hold the workby the blue surface. Clamp in a vee block to the XY table. The vee block can then be shimmed as necessary to bring the red face to a satisfactory degree of tramming to the Z axis.

Again size of the red surface and the final alignment of the red and purple machining planes is necessary as this will dictate the degree of difficulty you face. If the red fac

e is 200mm square problem is very different from the one in which the rd face is only a few mm square. Obvious but all too easy to miss when in a CAD drawing stage.

I still think the production process needed to consider the end result. I assume this is a retro modification in which case you the finished product / cost to start again and machine the critical faces at one setting or to have a sacrificial part such as your blue zone that is easy to reference - think square bar stock - prepare two faces as reference surfaces / edges from which all dimensions are made. The sacraficial paert being removed as the final machining operation.

You need a sensitive way of tramming the red face to the Z axis if you are going to achieve your goal of a few microns. Consider making a jig that will fit in the Z axis collet. The end surface being machined square i.e. is orthagonal to the Z axis. The red face of the work should then be clamped hard to the jig and care taken to shim a vee block to support the lck and shims. However this will be tedious and have to be repeated for each and every part.

If you need better accuracy then consider mounting a glass optical flat orthagonally to the Z axis. The flat must over hang the jig so that you can see \through the glass. Lower the glass flat onto the red plane of the work very slowly with some thin oil or even water on the red surface. As the glass flat approaches the red face the liquid will suddenly flood the face of the glass. Withdrawing the Z axis will streach the liquid film and you will see if the breakaway is even or if one edge consistently breaks first in which cas that edge is low and is adjusted and the process repeated. With a ground face on the red part you should achieve a good indication with water and a drop os detergent or photographic wetting agent in the water. This is very very tedious and you may like to consider starting to make the parts again.

Hope this helps crystalise your thoughts.

Regards

Pat

[roninB4]

This sort of orientation is usually best served by the use of a tooling ball, if there's no provision or possibility of using one then I'd suggest you construct a simple gauge/fixture to help yourself. Use of a known diameter rolled up against the angled surface yields the Z distance as well as the distance in the other axis (X or Y, whichever you have in the drawing). The critical thing here is how close you need to work to. You've stated that you need to work to microns, that means you need to have a diameter that can be well within (1/10) of your tolerance range.

As for using a mechanical edge finder (as opposed to an electronic one), there's the possibility of it digging into the surface as it slams into the surface with every rotation, mars the surface/unreliable numbers. Mechanical edge finders and wigglers should not be used when working closer than .127mm IMO as they just shouldn't be trusted. Work that close calls for the use of an indicator. If working to 10 microns (.0003937) a standard "tenths" indicator should be fine. If less than 10 microns you have many more factors to consider (temp, machine condition, set up accuracy, instrument accuracy, etc.). Since I don't know the workpiece, machine, or operation I can't suggest much more. I will state that if you've got 50 pieces of rework that are close tolerance you should obtain/make some close tolerance gauge/fixture to help yourself with. I hope this was of some help.

[Ashish B]

Hi All.

Well was busy in a project so couldn't reply.

We tried pickup with aid of edge finder & u will be curious to know that it works. U get a moderate amount of precision ( 20 micron ) & i guess that is the accuracy what Machining centre can offer for you.



What u need to do is pickup the edge finder Z offset ( at the centre of the shaft so as to enable you to rotate the Rotary axis around a defined position ) & than pickup the coordinates & than plot it in a CAD & than calculate apparent angle between them.

Well this is also very sure that the whole procedure is very time consuming, needs a communication between the CAD person & the operator.....The kick should be observed very carefully......& preferbely a edge finder in a very very good condition is a must.

But as we all were talking for a alternative for aliging the parts to X-Y plane of an indexing head...Its just a alternative procedure but definately not a practical solution.

Well the part i mentioned in the previous post had a slope so it could make up, but what about dowel holes when they are on diameter or a face... ( Radial & axial ways )...

Then What ?????????????????............It the big question.

I know Reinshaw offers the same type of alignment....( for pickup of slope ) but neither it has any option for Holes on circumference of the part & nor on the face of the part.

Well, have anyone heard about any standard procedure or a instrument for pickup & aligning the plane in a desired angle or XY plane within seconds....??


Ash


Thanks for your time, patience & support.

[Charlie Gary]

Originally Posted by Ashish B Hi All. Well was busy in a project so couldn't reply. We tried pickup with aid of edge finder & u will be curious to know that it works. U get a moderate amount of precision ( 20 micron ) & i guess that is the accuracy what Machining centre can offer for you. What u need to do is pickup the edge finder Z offset ( at the centre of the shaft so as to enable you to rotate the Rotary axis around a defined position ) & than pickup the coordinates & than plot it in a CAD & than calculate apparent angle between them. Well this is also very sure that the whole procedure is very time consuming, needs a communication between the CAD person & the operator.....The kick should be observed very carefully......& preferbely a edge finder in a very very good condition is a must. But as we all were talking for a alternative for aliging the parts to X-Y plane of an indexing head...Its just a alternative procedure but definately not a practical solution. Well the part i mentioned in the previous post had a slope so it could make up, but what about dowel holes when they are on diameter or a face... ( Radial & axial ways )... Then What ?????????????????............It the big question. I know Reinshaw offers the same type of alignment....( for pickup of slope ) but neither it has any option for Holes on circumference of the part & nor on the face of the part. Well, have anyone heard about any standard procedure or a instrument for pickup & aligning the plane in a desired angle or XY plane within seconds....?? Ash Thanks for your time, patience & support.

Any time I need to verify an angular setup, I use CAD/CAM software to draw two points on the plane. (I use software to save time- I could use a calculator and trig, but this is the 21st century) I then determine the distance between the two points (for example, z-1.4582 y+1.4582). I can then set a test dial indicator on the part and use a little program to run the indicator up and down the angled face to check it. If I use absolute positioning the program is simple-
N1 G01 Z-1.4582 Y1.4582 F20
N2 Z0 Y0
N3 GOTO N1

If the positioning is incremental, the program looks like this-
N1 G01G91 Z-1.4582 Y1.4582 F20
N2 Z1.4582 Y-1.4582
N3 GOTO N1

Either one will make the indicator run up and down the angle you are checking, but using the incremental program will mean you need to finish by manually entering a G90 to keep everything from going bad when someone tries to make a part.