[vlmarshall]

..Alternately you could have the wheel with the tools fixed in place, and an arm to pivot between it and the spindle to move the tools between them.

Ah, like a tiny version of Haas' side-mount tool changer...man that thing is scary, I always feel like it's waiting to hurl a toolholder at me during a change... bringing new meaning to 'facemill'.

[youngjim]

As much it would make a cool video, I've never heard of it happening. In any case this possible arm wouldn't have to turn very fast, even to go from one stop to the other in two or three seconds. The other thing you could do with this is have a pneumatic cylinder on the end of it to move the tool up and down, rather than use the (comparatively slow) Z axis. That way even with the moving parts moving at a calm pace, you could change tools pretty quickly.

Jim

[BobWarfield]

Somebody should build a horizontal machining center. They have a number of advantages over the verticals, but I would think particularly for a small machine in a garage shop, they'd be a win. They're supposed to be more rigid, and having help from gravity to clear chips would be a blessing.

Cheers,

BW

[GaryCorlew]

I have had this happen on a VF11 the tool is a rough boring head probably weighs about 30 or 40 lbs!!

Ah, like a tiny version of Haas' side-mount tool changer...man that thing is scary, I always feel like it's waiting to hurl a toolholder at me during a change... bringing new meaning to 'facemill'.

[escott76]

I have had this happen on a VF11 the tool is a rough boring head probably weighs about 30 or 40 lbs!!

The Hurco at work had a phase of doing that because of a couple of sticky pins. Sucked, but boy does it train you to keep the door closed when changing tools just in case.

[Starleper1]

I'm not worried about tools flying out. I don't plan on spinning it that fast. Also I don't plan on doing very large parts on this mill so the tool holder on the X axis won't be a problem. But i appreciate all your idears/comments.

I should be ordering all the major components in the next week or two. slides/ball screws/electronics etc..

[Smitty911]

Great looking Mill, I like the added Y cutting area.

Do you have a BoM? Or just order two sets and send be the left overs.LOL

It appears you could increase the tool holder by at least 3-4 more tools by narrowing the gap between holders.

Smitty

[Starleper1]

Great looking Mill, I like the added Y cutting area.

Do you have a BoM? Or just order two sets and send be the left overs.LOL

It appears you could increase the tool holder by at least 3-4 more tools by narrowing the gap between holders.

Smitty

what do you mean BoM?

I don't feel the need for more tools. 8 should be plenty for anything I'm going to make.

[Smitty911]

B0m is used as a Bill of Material, All the stuff you have to order for completion of the project.

Your right about the 8 tools didn't think of that.

My CNC X-2 has a small work area, by time you clamp parts down or the vise. I'd be intrested in making one of these bases.

Like I said Nice design, I really like the tool changer. That could come in handy.

Smitty

[cyclestart]

Somebody should build a horizontal machining center. They have a number of advantages over the verticals, but I would think particularly for a small machine in a garage shop, they'd be a win. They're supposed to be more rigid, and having help from gravity to clear chips would be a blessing

How well would a traditional HMC design scale down ? The only ones I've used were massive beasts with pallet changers and enclosures big enough to climb around in. The smallest I've seen up close had no enclosure but was still larger than a BP. A hobby size HMC would be awesome.

Nice design starleper1. Apologies if my post is a bit OT.

[Starleper1]

Small update. I started painting some of the parts, and also did a little more modeling.

[dang]

Nice work so far. Have you thought about filling in the base and column w/ epoxy/granite?

[Starleper1]

haha yeah right. It's a good idea but theres no way i would be able to move it. It ways a ton already.

[HawkJET]

Nice work so far. Have you thought about filling in the base and column w/ epoxy/granite?

haha yeah right. It's a good idea but theres no way i would be able to move it. It ways a ton already.

Also saving weight isn't always a good thing in machinery.

I'm confused, are you really concerned about weight or not?

Also, casting the epoxy/granite will help with some of the design shortcomings and really increase the rigidity. There are a number of things that I can see that undermine rigidity with the design. Epoxy/Granite will probably add around 50 - 60 pounds and would "cover a multitude of sins" (so to speak).

[Starleper1]

well just to make this clear. I don't plan on machining d-2 tool steel. For what I plan on using it for, it will be plenty rigid.

[HawkJET]

it will be plenty rigid.

There are very basic deficiencies in the design (from what I see in the pictures). A chain is only as strong as its weakest link. Your design has some very robust links that are connected by the equivalent of staples. I just don't think it will be as rigid as you think.

Why build your X axis in a way that the big boys do to make the machine rigid, and then throw it all away by cutting away most of the material for clearance for the Y axis bearings? You just shot yourself in the foot.

There are several other features that undermine rigidity in more severe ways. These are rudimentary aspects of mechanical design. If you follow the basics, you can increase the rigidity by a factor of five or ten. It would barely add any extra work so the bang for the buck is enormous!

I personally don't understand why you would put in all the work just to have a "tolerable" machine when you could do a few things differently and have an excellent machine.



I've seen many posts where the poster has jumped in with both feet and shown us his work, only to find that if he showed the plans first, some major flaws could be avoided (along with all the time spent). I always thought that the reason to participate in these forums was to learn and share.

As a Mechanical Engineering Consultant, I seem to have a way of looking at things that many others don't. Frankly I am surprised that I am the only one mentioning these design flaws. I guess it points to the need for some engineering background in this forum.

[Dougal]

There are very basic deficiencies in the design (from what I see in the pictures). A chain is only as strong as its weakest link. Your design has some very robust links that are connected by the equivalent of staples. I just don't think it will be as rigid as you think.

Why build your X axis in a way that the big boys do to make the machine rigid, and then throw it all away by cutting away most of the material for clearance for the Y axis bearings? You just shot yourself in the foot.

There are several other features that undermine rigidity in more severe ways. These are rudimentary aspects of mechanical design. If you follow the basics, you can increase the rigidity by a factor of five or ten. It would barely add any extra work so the bang for the buck is enormous!

I personally don't understand why you would put in all the work just to have a "tolerable" machine when you could do a few things differently and have an excellent machine.



I've seen many posts where the poster has jumped in with both feet and shown us his work, only to find that if he showed the plans first, some major flaws could be avoided (along with all the time spent). I always thought that the reason to participate in these forums was to learn and share.

As a Mechanical Engineering Consultant, I seem to have a way of looking at things that many others don't. Frankly I am surprised that I am the only one mentioning these design flaws. I guess it points to the need for some engineering background in this forum.

Ease up on the poor guy. This is a forum mainly full of enthusiastic hobbiests, it is not a showcase for cutting edge machines with hundreds or thousand of hours of design time invested in them.

I am also a mechanical engineering consultant and I have healthy regard for "specification creep". There's no point having an "all singing and all dancing" machine if it only has to walk occasionally and never has to sing or dance. In most cases the builders time was better spent elsewhere.
All projects turn into learning experiences and the lessons people teach themselves stick far better than the lessons others try to teach them.

[HawkJET]

There's no point having an "all singing and all dancing" machine if it only has to walk occasionally and never has to sing or dance.

He's building a VMC! It's INTENDED to be an "all singing and all dancing" machine!(chair)

I have healthy regard for "specification creep"

If you are building an airplane and use 4-40 screws to attach the wing, and I say use BIGGER BOLTS, is THAT "specification creep"???

In most cases the builders time was better spent elsewhere.

How much time does it take to use larger bolts to attach a wing?

All projects turn into learning experiences and the lessons people teach themselves stick far better than the lessons others try to teach them.

NOBODY lives long enough to learn by making all the mistakes themselves. One of the great things about a forum like this is that we have an opportunity to learn from others!

Jeeees! You have such a fragile ego....

[veteq]

Hello guys,

I have to agree with Hawkjet, it looks nice with those cad jpegs, but there are some "problems" in the design. I`m a automotive engineering student and based on basic mechanical knowledge i will give a view pointers.

The 2 beams that make the x-axis are just like the design off
Arie Kabaalstra, concept is seen on bigger VMC`s, but in this case all parts are smaller,lets say the height off the beam is 1,5 inch, but with the cutouts for the bearingblocks off the y-axis only max 0,5 inch.
(max cross section is 33% of the hole stock material,
on a bigger vmc the cross section is maybe 10% lees than the stock
cross section, because the scale is bigger).

It would be the almost the same as using beams off 0,5 inch thick,
for maximum stress in the material it would`n be a problem, but for deflexion it is just a lot more bending. (also wrapping off the material after machining)
It would be a lot better to change the design a bit and use the full 1,5 thick beams. (30 dollar extra material cost and 1 day machining, maybe 1 inch loss off z-axis motion?)

For the machine base i think you should use EG, where the to arms of the L-frame come together the moment is the largest. its connected with bolts. (bolts make the constrution at least 5 times weaker/less stiffer as a solid piece)
If you use EG you can also make the cross sections of usefull material a lot bigger and thus stiffer, also its then 1 piece and the problems off the bolts are gone. there`s also better resistence against vibration.

You could box the ballscrew with sheetmetal and then pour EG, Maybe you could use some bolts in the frame as anker.
( use a system that makes it possible to acces the ballscrew for maintenance)

almost forgot, see it al as positieve feedback. (offcourse)
Love to see the endresult, make the best off it.
nice job so far, keep it up.

kind regards,

Roy B.

[Starleper1]

I appreciate all the comments/concerns. You could be right, but for now I will just keep it as is. If it so happens, that the machine is not rigid enough for my liking, I will go back and adjust. Anyone who has ever built/engineered anything in their life can say that there is always revisions to any design. Everyone has their own way of doing things, so I'm not saying your right or wrong.