tips on building work centre components (board)

[Scipione205]

Hello.

I'm helping kids to build an economic and open source work center. we have aluminum components to be realized (square plates, holes and grooves for references).
I have been no longer working in the workshop, cam etc. for more than 5 years, so I ask for advice and help.

one of the fundamental objectives is the total cost, so the machine is made for most of the ready components, and in little part components made specifically (realized however with the machine itself).

I designed the plates so that they were simple to make, and I should have done it on a vf2. But then that workshop had problems and I had to look for solutions from third parties.

the estimates had so far go too far out of budget (it was actually initially expected zero cost for these components and I would have made them aggratis), but more than anything else I am sure that many workshops have bounced us because looking at the tables will have slipped.

Actually the holes should be lamature for cylindrical screws, or threaded blind holes. However to make the processing simpler, I made all normal holes passing, so that the holes can be realized all on the same side with drilling tips and drilling operations. then in the lab I will make tears and threads.

for the pieces "shoulder" I have designed alternatives that are plates, without the "strange" form, since for those pieces I need only parallelism between the main planes, the groove seat for ink that is in the picture, and then a border only in squadron with the planes and the groove (which then I use to control the alignments); that "strange" profile only serves to free space of space, and we can go with the tape saw in the lab.

about tolerances.
I need the planes to be parallel, and the edges to be squared between them and the planes, so that the assembly can be easily put into geometry. instead the holes are deliberately wide enough, so that there is room to adjust in assembly. there are grooves for reference pins of skates and guides, and the pieces "shoulder" and "often skates y" are framed in the seat, with a very light game so that the thickness can flow in during the assembly.

In fact I did not calculate the really necessary tolerances, it would suffice me the tolerance obtained from the machine (if it is in geometry, in good state, all executed correctly). in the past the same pieces I made them with a Chinese vertical cutter with swallow tail guides made cnc and I was more than satisfied.

Here I inserted geometric tolerances of 0.02 everywhere on a friend's advice. 5 cents would definitely be fine.

if you have advice on how to improve the table, change tolerances, to whom to address us, etc., I would be grateful.

when everything is final we will publish all the documentation so that anyone can make the machine. projects will never be on sale.

 

[Scipione205]

 

[ilmor]

Are you sure you need those tolerances?
to realize details with those tolerances of course the price is high. .
take into account that then you have to verify them.

 

[MassiVonWeizen]

to fly:
How do you get the material?
if from a supplier you ask for quotes to those who make laser cutting that guarantees you perpendicularity and parallelism and already makes the holes passers.
quotation:
in general, considering that what matters most are the holes all the tolerances on the sides of perpendicularity are too much. in general the odds of the holes or are given by a half board or must start from the same edge
the perpendicularity and parallelism on the 2mm friezes do not make sense because it is a feedback joke that if even it was wrong of 0.2mm it would work equally; In addition, if the milling process fails that tolerance means that all the rest of the piece is to be thrown.

 

[Scipione205]

Are you sure you need those tolerances?
to realize details with those tolerances of course the price is high. .
take into account that then you have to verify them.

it is necessary that the pieces are in squadron as they mount with recirculation guides of spheres. then during the assembly, to put in geometry the machine, I need references.
I don't mean to ask for a work with metrological reports.
when I made these same pieces (significant differences, but these were) with a small and Chinese cutter, I did everything damblé without problems and everything was fine. only thing the seats in the pieces "shoulder" I made them after making "often_pattini_y" putting bigger diameter in the cam, and I controlled by sliding the piece inside. ah, and the thicknesses (both y and z) spyed together so that the thicker was equal.

to fly:
How do you get the material?
if from a supplier you ask for quotes to those who make laser cutting that guarantees you perpendicularity and parallelism and already makes the holes passers.
quotation:
in general, considering that what matters most are the holes all the tolerances on the sides of perpendicularity are too much. in general the odds of the holes or are given by a half board or must start from the same edge
the perpendicularity and parallelism on the 2mm friezes do not make sense because it is a feedback joke that if even it was wrong of 0.2mm it would work equally; In addition, if the milling process fails that tolerance means that all the rest of the piece is to be thrown.

for both suppliers and brokers. I have no dimisticity with fiber lasers, I don't know how perpendicular the cuts (in theory the walls should still be conical), I just knew that with fiber we talk about tolerances a little more than a tenth.

What do you mean by saying that they have no sense of perpendicularity and parallelism of the feedback jokes?

However, I now check the guidebooks well.

 

[MassiVonWeizen]

What do you mean by saying that they have no sense of perpendicularity and parallelism of the feedback jokes?

see image.
However all those tolerances involve a lot of processing even to make the thickness from 15 or 18.

 

[Scipione205]

see image.
However all those tolerances involve a lot of processing even to make the thickness from 15 or 18.

I get it. I looked at the guidebook, it does not require perpendicularity for shoulders. Perhaps as you say, just touch a clove (and not all the surface of 1.5mm) for positioning (then you tighten the screws and you should not move, except collisions).

for the precision and precarious class of guides we mount, the admissible resting of mounting surfaces (for a distance of 500mm interasse):
- 25 thousandths of parallelism;
- 13 cents of height shock.


So I thought we had to stay with two cents. a friend then told me that normally they expect 3 cents of drawing for the pieces they usually do, without asking for metrological reports and they are well. I do not remember that tolerances are obtained from a good working center, in geometry and in good state, with tools and placements performed well. I remembered that on pieces less than this size, 5-3 cents was not a problem.

 

[MassiVonWeizen]

I do not remember that tolerances are obtained from a good working center, in geometry and in good state, with tools and placements performed well. I remembered that on pieces less than this size, 5-3 cents was not a problem.

Of course, it's not a problem, but tolerances must be put where they need and not "so the machine respects them without problems"
for example on all side surfaces that do not mate (see examples in images) what do they serve? Nothing. What do you mean? No. Does the processing price raise you? Yes.

 

[Scipione205]

parallelism between faces is indispensable; the edges are indispensable to be in squadron because I use them as a reference when I go to mount. Unfortunately, everyone.