Hobby project

Everybody needs a hobby project. One with no deadline, one that fits in between your real projects. Here is my hobby project - it will be a multi-machine-tool built from the ground up. It started life just to be a surface grinder but grew into a vertical mill and then also a shaper. I do not usually make models first but this time I have partially made a wooden mockup. This will also become a working model before the real thing gets built.

Here is the Statement of Intent video

https://youtu.be/Tz1nnaxdgQc

Thanks, Tony for sharing your thoughts on your project and the tip to the interesting mechatronics site.

FWIW: Given that an epoxy-granite filled gantry will be more rigid than a single vertical support of any design,
one remaining problem will be the gantry-to-spindle overhang distance (for the given precision of the linear rails).
Humble tip: You could mount the vertical rails on the outside of the gantry, to:
1) utilize the rail's inherent rigidity from their greater width (rather than their height, and perhaps even wider distance between the top and bottom bearing) and
2) thus improving overall rigidity by reducing the spindle overhang with app 30 mm.

In Leibnitz' perfect world - one could perhaps imagine a rigid, high rectangular box around the gantry,
with the horizontal rails inside and spindle centre at the centre of the gantry's footprint?
Unwieldy, heavy and cumbersome of course, but optimized rigidity given the components involved.

Just my two cents...
ATB and good luck!
Johan

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Originally Posted by DIYSwede

Thanks, Tony for sharing your thoughts on your project and the tip to the interesting mechatronics site.

FWIW: Given that an epoxy-granite filled gantry will be more rigid than a single vertical support of any design,
one remaining problem will be the gantry-to-spindle overhang distance (for the given precision of the linear rails).
Humble tip: You could mount the vertical rails on the outside of the gantry, to:
1) utilize the rail's inherent rigidity from their greater width (rather than their height, and perhaps even wider distance between the top and bottom bearing) and
2) thus improving overall rigidity by reducing the spindle overhang with app 30 mm.
Just my two cents...
ATB and good luck!
Johan

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I did consider putting the vertical rails as you suggest but having decided to use plain granite slabs for the slides, and my lifelong membership of KISS, it was what the youth call a no-brainer to put the rails on the face.
However, I do plan on counterweighting the assembly, see these videos for hints on how I might do that.

https://youtu.be/IqUbrcYlG8k

and

https://youtu.be/6XDrUhMqYgw

Here is a very short video showing the preparation of the bottom granite slide. Even with the wooden working model all the slides will be the final granite versions.

https://www.youtube.com/watch?v=BVSNL2mTcOg

Hi Tony, I'll watch you build this machine with great interest having gone through similar planning stages when building my surface & cylindrical grinder.
I note you haven't mentioned grinding dust protection for the rails and ball screws. Are you relying on the built in dust seals of the linear bearings as its only occasional light duty use? Dressing the grinding wheel will cover all those precision parts.
Have you considered using coolant when grinding and drainage of same?
The vertical control movement should be as fine as possible for grinding. I used a motor for rapid up down, then switched to hand feed to the ground surface with a very fine adjustment. There will be some conflict of priority between the mill/shaper and surface grinding feed needs.
Lovely challenge!

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Originally Posted by albertq

Hi Tony, I'll watch you build this machine with great interest having gone through similar planning stages when building my surface & cylindrical grinder.
I note you haven't mentioned grinding dust protection for the rails and ball screws. Are you relying on the built in dust seals of the linear bearings as its only occasional light duty use? Dressing the grinding wheel will cover all those precision parts.
Have you considered using coolant when grinding and drainage of same?

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All of your concerns will be addressed.

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Originally Posted by albertq

The vertical control movement should be as fine as possible for grinding. I used a motor for rapid up down, then switched to hand feed to the ground surface with a very fine adjustment. There will be some conflict of priority between the mill/shaper and surface grinding feed needs.
Lovely challenge!

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Fully motorised with a commanded resolution of 1 um. I can't match that by hand. There will be no conflict of priority. The motor will put the head where it is told without concern for whether it is a mill or grinder.

Watch this space. Maybe you will like this horizontal version

https://youtu.be/d1Px54tl6aQ

Quote:

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Originally Posted by albertq

Hi Tony, I'll watch you build this machine with great interest having gone through similar planning stages when building my surface & cylindrical grinder.

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I had another look at your grinder to refresh my memory. You did a great job of that. I see that I made a few comments which I had forgotten. To bring those comments up to date.

1. I mentioned planning a surface grinder, well that is the focus of my current post. There has been a long gap but as I mentioned in the recent video I was not happy with any design until I recently thought about using the gantry construction.

2. I also mentioned a CNC cam grinder. Well that has been built and works up to expectations or hopes. It is based on a lathe but only to get a solid base, the X axis runs on ball rails and is driven by a ball screw, and is what controls the infeed. Rather than use the lathe head stock I fit an electronically controlled rotary table as the workhead which has a resolution of 0.01 deg.
When not doing duty as a cam grinder it becomes a CNC cylindrical grinder. Being CNC means than I can grind tapers from software, no mechanical alignment setup needed. So no need for test cuts.

Now that yours is a couple of years old is there anything that you would do differently if you were doing it again?

I will make a progress update post in the next day or two.

I think you have all the main bases covered Tony, enjoy the project. If I understand your design correctly, for surface grinding you will be using a vertically mounted cup-grinding wheel.
So far happy with both cylindrical and surface operation and no regrets using it as designed.

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Originally Posted by albertq

I think you have all the main bases covered Tony, enjoy the project. If I understand your design correctly, for surface grinding you will be using a vertically mounted cup-grinding wheel.

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No, you do not understand the design correctly. The grinding wheel will be mounted in the normal, non-Blanchard, surface grinding orientation. See how I am holding the grinding head in the video.

Although I have used a cupped wheel in the mill for some surface grinding operations. With a CBN grit that can produce very nice finishes but cooling is very important because these wheels are usually built on an aluminium cup and if allowed to get warm they will expand and increase the depth of cut and then produce more heat, expansion and increase the depth of cut and then produce more heat, expansion and depth of cut.....until very bad news.

[QUOTE=tonyfoale;255171]No, you do not understand the design correctly. The grinding wheel will be mounted in the normal, non-Blanchard, surface grinding orientation. See how I am holding the grinding head in the video.

Ok now I think understand, the grinding spindle will hang horizontally below the cross plate so as to clear grinding wheel.

[QUOTE=albertq;255185]

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Originally Posted by tonyfoale

Ok now I think understand, the grinding spindle will hang horizontally below the cross plate so as to clear grinding wheel.

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The spindle will not be below the cross plate it will be about "wheel radius - 15 mm" ABOVE the bottom of the cross plate. On the face of the cross plate there will be a pair of horizontal linear rails, 28 mm thickness, onto which will fit the third (X axis when configured as a mill) granite slab of 22 mm thickness. So the outer face of this slab will be 28 + 22 =50 mm away from the outer face of the horizontal slab (Z axis when configured as a mill). The grinding head will mount on the third slab and the wheel and guard will overhang to one side. 50 mm + the radius "spindle to the base of the grinding head" gives ample clearance for the wheel and safety guard.

I'll make a sketch and post it. Unlike your excellent post I have no physical drawings or sketches, although I do have mental pictures of it all.

Imagination and mental pictures are all you really need Tony. I'll watch you create it with interest.

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Originally Posted by albertq

Imagination and mental pictures are all you really need.

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I have have no shortage of those, but here is a paper picture. My mental pictures have straighter lines.

Attachment 49689 Click for full size.

Since the video with rough sawn wood I have milled the individual wood sections square. Then I milled the assembly where it matters. The wooden mockup has been useful for checking out how I can fit the final metal version in the mill for alignment and machining. I did not size the thing based on what I could machine but the sizing came from the size of the magnetic chuck plus some overrun. With a large flycutter in the mill I can just cover it where necessary. A function of luck.
For now I will have a rest from the physical side and concentrate on designing and making the controller and writing the software. Then I'll be able to check powered movements.

Attachment 49690 Attachment 49691 Setup alignment.

Attachment 49692 Attachment 49693 Needs controller and software to test.

The bearing housing and motor mount are what I had and they fit. For the final metal version they will be combined into a single piece housing. That will ensure concentricity and there will be less setup needed.

Looks like something that you could pour out of high strength concrete and have quite the rigid tool. The gantry uprights could have integrated compression rods if you were worried, or you could alternatively mix in a fibrous binder.

Been thinking along similar lines for a CNC mill and possibly lathe.

Mark

Hi: Looks like a very good start! Here are my suggestions: Mount the ball slides as far apart as possible, would make the table more repeatable and stable. Look at adding flood coolant, it makes a huge difference by keeping the work cool and flushing the chips away. When I grind without coolant I often get burn marks.
The concrete bed and frame is a valid idea, some modern machines use epoxy/granite frames, I have epoxy/granite surface plate that was once certified.
Carl. (ps: I designed grinding machines at work)

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Originally Posted by mwmkravchenko

Looks like something that you could pour out of high strength concrete and have quite the rigid tool. The gantry uprights could have integrated compression rods if you were worried, or you could alternatively mix in a fibrous binder.

Mark

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I did mention in the video that my original thoughts were to use epoxy/granite, for the frame, which I regard as superior to concrete. Neither epoxy granite nor concrete are very rigid. Just look at their Young's modulus. Both rely on steel for rigidity. For rigidity where do you get the best results from the steel? You get the best results when the steel is at the surface. Just consider their I, moments of inertia. Hence my choice of steel tube filled with epoxy granite. In addition it is so much easier to make.

Quote:

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Originally Posted by carl blum

Hi: Looks like a very good start! Here are my suggestions: Mount the ball slides as far apart as possible, would make the table more repeatable and stable. Look at adding flood coolant, it makes a huge difference by keeping the work cool and flushing the chips away. When I grind without coolant I often get burn marks.

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All valid points which are in the plan.

Quote:

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Originally Posted by carl blum

The concrete bed and frame is a valid idea, some modern machines use epoxy/granite frames, I have epoxy/granite surface plate that was once certified.
Carl. (ps: I designed grinding machines at work)

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I have a thicker plate of solid granite which I am still considering as the base on top of epoxy granite filled steel tubes.
What is/was the benefit of an epoxy granite surface plate over the more usual solid granite plate?
(PS. I did not design grinding machines at work) So please outline using your experience, for the benefit of us all, just what features you have found to influence surface finish.

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Originally Posted by tonyfoale

I did mention in the video that my original thoughts were to use epoxy/granite, for the frame, which I regard as superior to concrete. Neither epoxy granite nor concrete are very rigid. Just look at their Young's modulus. Both rely on steel for rigidity. For rigidity where do you get the best results from the steel? You get the best results when the steel is at the surface. Just consider their I, moments of inertia. Hence my choice of steel tube filled with epoxy granite. In addition it is so much easier to make.

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OH YES .... SOOOO... much easier.. AND for looks, Why not add stick on "Carbon Fiber" signwriters vinyl ? (HeHe Dad's joke)

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Originally Posted by michaelmacnz

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OH YES .... SOOOO... much easier.. AND for looks, Why not add stick on "Carbon Fiber" signwriters vinyl ? (HeHe Dad's joke)

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I did consider that but the coefficient of vinyl thermal expansion does not match that of the steel base.

https://www.youtube.com/watch?v=hScHgGRTEuk

Just a bit of information that is well explained and practical. There are quite a few more useful videos in this channel. I've mixed and poured epic amounts of concrete. I learned a fair bit watching some of these videos.

Mark

Not sure how you plan to bolt the vertical tube frame to the horizontal tube frame, but I would add two plates at the bottom of vertical frame as "T" to allow for the torque applied when shaping a tall piece of metal. Also leave sufficient grinding wheel clearance below vertical axis granite to dress the wheel substantially smaller.
I have no doubt you have thought of all this already.

Attachment 49705

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Originally Posted by albertq

Not sure how you plan to bolt the vertical tube frame to the horizontal tube frame, but I would add two plates at the bottom of vertical frame as "T" to allow for the torque applied when shaping a tall piece of metal. Also leave sufficient grinding wheel clearance below vertical axis granite to dress the wheel substantially smaller.
I have no doubt you have thought of all this already.

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Better than the plates is the planned bracing on the metal version. I rotated the pic. to avoid confusion as to which are the horizontal beams.

Attachment 49706 Click for full size.

I have had messages suggesting that the bottom rails were too close together. They are not, they are spaced optimally. Consider the sketch.

Attachment 49707 End view.

Granite is a brittle material and in common with some other materials such as concrete etc. is best not used in tension or bending. My designed spacing uses the granite plate to provide damping and is stressed basically in compression as a spacer. It is not really structural. I do nothing by accident.

The Z and Y axes (in mill config) will have the rails spaced much farther apart, as will become apparent in a future post the other two plates will be also used mainly as spacers providing mass and damping.

I have made a new post for part 2 of this project, you can find it here https://www.homemadetools.net/forum/...876#post255812

The X axis is up and running, it lives.

Attachment 49762