doubts work/technological process

[AndretheGiant]

Hello everyone
Since I had the pleasure of being clarified several times about doubts I thought of opening a unique discussion where I could ask or disregard technological processes of machine tools and not only.

I immediately ask a question to inaugurate in a station like this where you have a cut that must be precise and respect the work of the holes as you would achieve it? thickness is 20mm
I think it would be better to work the pieces separately and cut a semicircle. Is there a way to make the alesed holes and then make a precise cut?

 

[TECNOMODEL]

Hello everyone
Since I had the pleasure of being clarified several times about doubts I thought of opening a unique discussion where I could ask or disregard technological processes of machine tools and not only.

I immediately ask a question to inaugurateView attachment 64826in a station like this where you have a cut that must be precise and respect the work of the holes as you would achieve it? thickness is 20mm
I think it would be better to work the pieces separately and cut a semicircle. Is there a way to make the alesed holes and then make a precise cut?

there are various solutions depending on the available machines, required tolerances etc.
One is what you said, work on cnc and do the 2 pieces individually.
you can, otherwise, make 2 pieces without ø25 holes, assemble them by interposing a thickness of 0.6 and then perform holes.
last solution, you make a single piece and you perform the cutting by wire electroerosion.
a note, but I imagine the design is not yours, any tolerance of 25h7 is quite absurd, considering that the 2 pieces are fixed only by the 2 screws.

 

[Mario SJPD]

any tolerance of 25h7 is quite absurd, considering that the 2 pieces are fixed only by the 2 screws

Exactly.
if you are right to proceed like this:
do the processing in two pieces the diameter 25h7 only rough, screw them, push them and proceed with the finishing of the hole, but at that point the quota 0.6 does not make sense.

 

[MassiVonWeizen]

probably h7 tolerance is used to ensure uniform contact on surfaces and 0.6 distance to ensure component locking.
with this system I designed several supports in two half for bearing housing (like commercial snl, but made ad hoc).
instead when I made the lathe I made many bronzine in two half; a pre-finish with overmetal, cut into a belt saw, made joint welding and worked to measure (unfortunately I don't remember if they had light between the two parts)

 

[meccanicamg]

Hello everyone
Since I had the pleasure of being clarified several times about doubts I thought of opening a unique discussion where I could ask or disregard technological processes of machine tools and not only.

I immediately ask a question to inaugurateView attachment 64826in a station like this where you have a cut that must be precise and respect the work of the holes as you would achieve it? thickness is 20mm
I think it would be better to work the pieces separately and cut a semicircle. Is there a way to make the alesed holes and then make a precise cut?

the only exact system at the centimeter is to build the three components, assemble them with the screws and make the two holes from 25h7. this is what you do with all the machinery where bearings and precision pieces go. Although we are in 2022 with middle operators and unreviewed machine tools you can not do the precise holes to the cent.

I forgot... ..you had to put a 0,6mm foil before making the two holes... ..so after throwing and you have the preload.

 

[AndretheGiant]

thank you so much as usual for the precious snacks.

a note, but I imagine the design is not yours, any tolerance of 25h7 is quite absurd, considering that the 2 pieces are fixed only by the 2 screws

The design is not mine, but it passed through my hands. I don't remember if he has thorns, I should see.. in this case, as described @meccanicamg wouldn't the centring be guaranteed by the tree itself that will be tight with the screws?

 

[AndretheGiant]

welded joints were made and worked to measure

I don't understand this passage, how can I cut and then rise?

 

[MassiVonWeizen]

I don't understand this passage, how can I cut and then rise?

Why if you don't somehow block the piece (saving, screws, thorns, ....) how do you work it? As you put it in the car and touch it with the tool happens a mess.
of course the welding would then be removed

 

[MassiVonWeizen]

instead when I made the lathe I made many bronzine in two half; a pre-finish with overmetal, cut into a belt saw, made joint welding and worked to measure (unfortunately I don't remember if they had light between the two parts)

I remembered that after the sawn cut the two surfaces to join were milled
allego an exemplifying pigry made with paint

 

[AndretheGiant]

I understand, with a certain thickness, you can make welds in the head

 

[MassiVonWeizen]

even if in the drawing I represented them to penetration (cause limit paint and my imagination) are not done so, but it is a banal cord that will be removed with a grinder.
in other cases where only the inner diameter is worked (e.g. https://www.comese-sennagiovanni.it/realizzazioni-cuscinetti-in-metallo-bianco.htm) and no bolt holes are used for clamping bands (I can't find pictures, but imagine two omegas that lock the two half and lock through bolts).
the choice depends very much on the detail and the equipment available

 

[AndretheGiant]

welcome to a new episode of “how is it done” :d

Today we talk about a turning piece that due to the particular positions of the fixtures must be obtained in two semi-flanges to be assembled. as you see the two 50 diameters must be perfectly concentric, the two semi-flanges will be centered between them with two thorns, if you see one in semisection. How would you find it so that everything is centered? I thought so: a round to 92 is worked, then from this it breaks into two and are made of two centerings from 50 separately and the internal thorns using the external worked 92 as a reference.

 

[TECNOMODEL]

welcome to a new episode of “how is it done” :d

Today we talk about a turning piece that due to the particular positions of the fixtures must be obtained in two semi-flanges to be assembled. as you see the two 50 diameters must be perfectly concentric, the two semi-flanges will be centered between them with two thorns, if you see one in semisection. How would you find it so that everything is centered? I thought so: a round to 92 is worked, then from this it breaks into two and are made of two centerings from 50 separately and the internal thorns using the external worked 92 as a reference.View attachment 64863

We overlook the absurdity of those unnecessarily complex pieces, we realize the 2 separate pieces respecting the tolerances on ø and puncture and stop.

 

[MassiVonWeizen]

I thought so: a round to 92 is worked, then from this it breaks into two and are made of two centerings from 50 separately and the internal thorns using the external worked 92 as a reference.

what sense does a ø92 make and then cut it to measure 14 (I think this you mean to tag it in 2)? and how would you return the diameter ø75?
take 2 round pieces and work separately.
the pieces are taken on the outer diameter with self-centering spindle and if you check that the rotation is perfect or within the 0.01 you will be sure that the holes will be equally.
if you don't trust you make the separate pieces with plugs and fixing holes, they mate with each other through the thorns and they block and then work the two holes (possibly you can give a couple of welding points on the ø75 diameter that will then be grinned to divide the two bodies)

please, if you want a proper insight, you need to attach all the design and not just a part; in fact we do not know the thorns if and how they are tolerated

 

[AndretheGiant]

Bye. I meant that from the same round we work both 92 and 75 and then we truncate to have the two pieces definitely concentric.

 

[TECNOMODEL]

Bye. I meant that from the same round we work both 92 and 75 and then we truncate to have the two pieces definitely concentric.

It's a useless and expensive complication, material throws, time and you have additional work to do.

 

[IronMike87]

there are various solutions depending on the available machines, required tolerances etc.
One is what you said, work on cnc and do the 2 pieces individually.
you can, otherwise, make 2 pieces without ø25 holes, assemble them by interposing a thickness of 0.6 and then perform holes.
last solution, you make a single piece and you perform the cutting by wire electroerosion.
a note, but I imagine the design is not yours, any tolerance of 25h7 is quite absurd, considering that the 2 pieces are fixed only by the 2 screws.

Why absurd? always depends on the functionality of the piece.
does not even have geometric tolerances associated with that diameter

If you want both holes you can always make them electro-erosion.
or with a normal drilling operation if the depth is not too high and there are no excessive deviations of the same (depending also on the material)
Moreover nowadays many multitasking machines have the possibility to mount a rectification head. so if you want to make the hole smaller, leaving the overmetal appropriate, and bring it to ø25h7 grinding (if the piece is not too high). in the same position. on the same machine "fresher"


to say, today there are such machines, eh

 

[TECNOMODEL]

Why absurd? always depends on the functionality of the piece.
does not even have geometric tolerances associated with that diameter

If you want both holes you can always make them electro-erosion.
or with a normal drilling operation if the depth is not too high and there are no excessive deviations of the same (depending also on the material)
Moreover nowadays many multitasking machines have the possibility to mount a rectification head. so if you want to make the hole smaller, leaving the overmetal appropriate, and bring it to ø25h7 grinding (if the piece is not too high). in the same position. on the same machine "fresher"


to say, today there are such machines, eh

It is absurd such a tolerance on a piece that is at all effects a clamp.
Besides the 2 "ganasce" are not even held in phase by thorns, columns or other.

 

[IronMike87]

Bye. I meant that from the same round we work both 92 and 75 and then we truncate to have the two pieces definitely concentric.

If for some reason I need to guarantee total concentricity (but I do not see specific requirements), what I would suggest is to perform a pass-through hole, calibrated ø_h7 or h9, of pure service, to be used as a reference source.

once you have turned and "separated" the pieces, in the next drilling and milling operation, you go to tastare the hole calibrated with the renishaw probe to bind the geometry, and the remaining holes are "guaranteed" in the required position

It is absurd such a tolerance on a piece that is at all effects a clamp.
Besides the 2 "ganasce" are not even held in phase by thorns, columns or other.

Mah. I do not allow me to judge the functionality of a piece without seeing the complete design (I only see a view there) and the axieme where it is mounted.

said this, if you frightened for such processing, I think that you have no idea the potential of current machine tools. a hole ø25h7 for what is made in opera on a assiemato, but without any specific request of internal roughness and true position, honestly it is little stuff in absolute terms of complexity of the processing



just to compare with something like this (yes also this is a assiemato)