Latest Project: A Universal Milling and Grinding Fixture (see pics)

[jgedde]

Yes, I'd be happy to share them when they're done. I'll have to chat with Nelson/Tony to get them all up on the site at once. The STEP files could end up being 30-40 MB all said and done.

On the other hand, I'd hate to see an exact copy of my design for sale at some import tool house CNCed from my files selling for less than the cost of the raw materials bought domestically, so I may just provide them upon request.

John

 

[jgedde]

John

Your design has one axis too many.

The base is needlessly weakened with the excessively elongated slots and the track for the t-slot key.

Gene

Gene,

As far as the axis count, I thought long and hard on that, but I maintain that the axis count is correct. If there were only three axes, you'd have to compute a compound angle at the toolholder... The fourth axis takes care of that. Remember, this isn't a CNC machine where the three axes would be sufficient. It's meant for ease of manual use.

The slots are longer than I wanted them to be, but at that length they handle the T-slot spacing on Bridgeports as well as import mill/drills. In reality though, the slots aren't too long, the base is too big. I did this to gain additional surface area when using a magnetic chuck and to allow the edge to come all the way to the edge of the chuck for the alignment plate.

I belabored the T-slot keyway depth and length as well as the thickness and size of the base. A coworker ran it through FEA on Pro-E. It made almost no difference whether the T-slot keyway was there or not. Agreed it doesn't need to be all the way across.

John

 

[easymike29]

Gene,

As far as the axis count, I thought long and hard on that, but I maintain that the axis count is correct. If there were only three axes, you'd have to compute a compound angle at the toolholder... The fourth axis takes care of that. Remember, this isn't a CNC machine where the three axes would be sufficient. It's meant for ease of manual use.

John

You are sacrificing rigidity for the convenience of the extra axis.

Gene

 

[jgedde]

You are sacrificing rigidity for the convenience of the extra axis.

Gene

Without a doubt. Convenience is what this thing is all about. There's no question a different fixture would do better for heavy milling: Like two angle plates bolted together with a calculated compound angle.

For grinding tools and cutters, it doesn't matter nearly as much since the forces are MUCH lower. The extra axis also allows for sweep grinding. Like standard ground drill bits. I don't plan on doing this since the design lends itself to 4 or six facet drill grinds.

For the hobbyist, making more light cuts and taking longer isn't nearly the issue it would be in a production shop. But, for onesies and twosies, convenience trumps. Who wants to spend two hours fixturing something for a 5 or 10 minute operation? Spending two hours fixturing something you'll use to hog metal all week? That's a different story.

If you want a brick &^%&house with one less axis, buy a Rockwell Univise (if you can find one for a good price - a tough proposition).

I believe the 3D models don't do the item justice as they don't show the welds. In real-life the thing will look much beefier.

John

 

[gmoushon]

Yes, I'd be happy to share them when they're done. I'll have to chat with Nelson/Tony to get them all up on the site at once. The STEP files could end up being 30-40 MB all said and done.

On the other hand, I'd hate to see an exact copy of my design for sale at some import tool house CNCed from my files selling for less than the cost of the raw materials bought domestically, so I may just provide them upon request.

John

Certainly understand your concerns...and don't blame you. I'm a hobby guy and have this propensity for starting projects and not finishing them. The design caught my attention and this project would be way down on my list of things to finish. Heck, I don't even have a surface grinder yet! (lol)

Keep the photo's coming...definitely enjoy watching the progression.

gm

 

[Hawkeye]

I think you're right, John. On-request is the better way to go. That will also let you know who and how many are planning to build your design. Always a nice thing to know when you've come up with something original.

 

[bvd1940]

Yes, I'd be happy to share them when they're done. I'll have to chat with Nelson/Tony to get them all up on the site at once. The STEP files could end up being 30-40 MB all said and done.

On the other hand, I'd hate to see an exact copy of my design for sale at some import tool house CNCed from my files selling for less than the cost of the raw materials bought domestically, so I may just provide them upon request.

John

I would greatly appreciate your consideration of my name on that request for a copy of the prints.
What are STEP files??? I am not real PC savvy.:thinking:
I sure would like to incorporate your universal holder in my dedicated tool grinder)

 

[easymike29]

John

With your fourth axis can you grind the "flat" along the sharp edge of a threading tool bit without first computing the angle?

Gene

 

[jgedde]

Gene,

Yes, the thread angle and relief angle can be ground simultaneously. The pointers are adjustable so the unit can be calibrated using squares.

John

 

[easymike29]

John

I was not referring to the thread and the relief angle. I was referring to the (.25P) flat at the apex of the 60 degree angle.

Gene