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Modular Fixturing for one-off prototype parts

steelrides

New member
I'm trying to figure out a good modular fixturing system that is well-suited to one-off prototypes. I'd invest some money into a system that would allow us to be more efficient on our CNC, so I'm curious what others are using to hold work.

For background, I own an engineering R&D firm and we have a BP Series 2 3-axis CNC (among a ton of other tools for prototyping in plastic and metal) but we just haven't figured out a good way to be efficient machining complex parts. Since we're designing most of the parts we build, we can often make them simple enough for holding in a vice or minimizing the operations to one or two sides. However, I'd like to be able to better hold more complicated shapes and register 2nd, 3rd, and more operations better. We're using Solidworks and create programs in CAM rather than conversational. I've designed and built fixtures and custom soft jaws for workholding but it can take as much time as fabricating the part itself. I'm almost wondering if adding a 4th axis would be way to tackle this. Thoughts?
 

mhajicek

Active member
All depends on the specifics of the parts. I've found soft jaws to be the quickest, easiest, and cheapest solution for most of my parts.
 

barbter

Banned
Also depends upon part sizes and whether they are families - ie similar and only a little different.
Standard billet sizes obviously work too - you can tool up efficiently with holding jaws or mitee bites or even pre-opped plates with drilled/reamed holes so you can pull back or bolt down etc onto a sub plate.
Lots of different ways to do this but it depends upon your parts
 

CBlair

Active member
In my opinion the best option for flexibility is the Pierson pallet system. Simple aluminum pallets you can machine to hold most anything flat or with surfaces you can clamp on. The base is about the same size as a vise and you can even put another plate on top of the regular pallet for a spoil board.

Have a look at it and see if it would be of help to you. Good for parts larger than convenient for the vise and for multiple parts or for more than one op at the same time. Not perfect for everything but a good value and it works for what it works for better and cheaper than other options I have seen.

Pro Pallet System – Pierson Workholding

Charles
 

implmex

New member
Hi steelrides:
Get a 5 axis turntable or better yet a 5 axis mill.
Mount a 5th axis or Lang vise system on it.
Dovetail all your blanks.
Go to town and make parts!
Program just about every part as a 5 axis part.

It sounds kind of snarky to say it this way but the reality is more and more shops are embracing 5 axis machining as a routine way of making their parts...even simple parts, for the same reasons you are complaining about. (feeling the limitations and inefficiencies of how you are doing it currently).

If your parts are all prismatic and do not require simultaneous 5 axis interpolation, you can fake it a couple of ways.
1) You can mount a little manual rotary table onto a CNC 4th axis rotary and put a dovetail vise on it.
2) You can build and mount 3 master blocks with their dovetails all at right angles to each other directly on the mill table, and transfer your part between them, either with a pallet on which you mount your dovetail vise or directly with the dovetail you've milled on your stock.
3)You can buy a contraption that forms the 5th axis turntable and mount it to a manual or CNC 4th axis rotary table.
One of the posters on here was showing off a system like that about a year ago that he was hoping to market just for guys like you.

These are all ways forward...obviously the fully integrated 5 axis mill gives you the best relative accuracy, especially if you buy a reputable brand (look for the recent thread on the woes of a guy who bought and then had to dump a UMC 500...the guy's name is "empwoer").

There is no other modular system that will give you so much, but it's not trivial to get into.

Cheers


Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 

e30ryan

New member
I mainly do one-off parts, and my main priority is speed of delivery (i.e. less than a day from order receipt to completed parts). Most of the parts I do are prismatic and don't involve much 3D surfacing. My solution for relatively quick setups usually involve a fixture plate, lots of varieties of strap clamps, narrow sine bar (for setting angles in a standard vise), and most definitely a Haimer 3D probe (probably my favorite purchase). My mill is just a simple 3 axis...

I have also bought into the Pierson pallet system which lets me switch between vices, fixture plates, etc. without having to dial them in.

One big time saver in terms of programming/CAM was to develop macros for simple things such as side milling to size (prepare saw-cut blanks) and face milling to thickness.

Not a fixturing solution, but definitely a time-saving solution is to have MANY tool holders. I can be efficient at my work because I don't spend time mounting and measuring tools.
 

steelrides

New member
1) You can mount a little manual rotary table onto a CNC 4th axis rotary and put a dovetail vise on it.
2) You can build and mount 3 master blocks with their dovetails all at right angles to each other directly on the mill table, and transfer your part between them, either with a pallet on which you mount your dovetail vise or directly with the dovetail you've milled on your stock.
3)You can buy a contraption that forms the 5th axis turntable and mount it to a manual or CNC 4th axis rotary table.

I like these ideas. I was sort of joking about adding a 4th axis which is probably in the $20k range for some used equipment, amplifiers, and control boards. However I've been looking at manual rotary indexers and tables for a while to add to my manual mill but hadn't considered the ability to have access to 4 sides of the part in one simple setup. I'll have to think about what types of parts this would be useful for, since I imagine they'd have to be fairly stout and rigid even with a tailstock.


One big time saver in terms of programming/CAM was to develop macros for simple things such as side milling to size (prepare saw-cut blanks) and face milling to thickness.

Not a fixturing solution, but definitely a time-saving solution is to have MANY tool holders. I can be efficient at my work because I don't spend time mounting and measuring tools.

Do you have a resource for building macros? I have no experience with that. Is it generic G-code or is it machine specific (Mach3 vs Fadal, for example)?

most definitely a Haimer 3D probe (probably my favorite purchase)

It didn't take long for me to figure out that an electronic probe is a huge time-saver for setting Z-height and finding X-Y origins. It's accurate to less than .001" and super fast and reliable. I made mine, but I don't have many tool holders that are permanently set. Each tool change is a new program, and I just set the Z for each tool change. Having dedicated toolholders would certainly be faster but an ATC would be a real upgrade.
 

Wsurfer

New member
This thread has me intrigued on some type of manual 3+2 indexing system. All rotations for my applications would just need 90 degrees on all axis. Does such an animal exist, or do you have to roll your own ?.
 

implmex

New member
Hi steelrides:
Look for a standalone Haas CNC rotary table with its own control box.
You can find them for varying prices in varying condition on Craigslist or on Ebay.
You can just mount them on your mill and run them...I don't believe you can interface them with your control without some jiggering, but you can run them stand alone, even on a manual mill.
I also believe they can only index, so no interpolation.

So you'd have to punch a button every time you index.
Not as good as a fully integrated solution you can just walk away from, but still better than fixturing and better than hand cranking a manual rotary table.

I've seen them on Ebay for a few grand, and really nice New Old Stock ones (HRT 160 sized) for around 8 grand.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 

empower

New member
Hi steelrides:
Get a 5 axis turntable or better yet a 5 axis mill.
Mount a 5th axis or Lang vise system on it.
Dovetail all your blanks.
Go to town and make parts!
Program just about every part as a 5 axis part.

It sounds kind of snarky to say it this way but the reality is more and more shops are embracing 5 axis machining as a routine way of making their parts...even simple parts, for the same reasons you are complaining about. (feeling the limitations and inefficiencies of how you are doing it currently).

If your parts are all prismatic and do not require simultaneous 5 axis interpolation, you can fake it a couple of ways.
1) You can mount a little manual rotary table onto a CNC 4th axis rotary and put a dovetail vise on it.
2) You can build and mount 3 master blocks with their dovetails all at right angles to each other directly on the mill table, and transfer your part between them, either with a pallet on which you mount your dovetail vise or directly with the dovetail you've milled on your stock.
3)You can buy a contraption that forms the 5th axis turntable and mount it to a manual or CNC 4th axis rotary table.
One of the posters on here was showing off a system like that about a year ago that he was hoping to market just for guys like you.

These are all ways forward...obviously the fully integrated 5 axis mill gives you the best relative accuracy, especially if you buy a reputable brand (look for the recent thread on the woes of a guy who bought and then had to dump a UMC 500...the guy's name is "empwoer").

There is no other modular system that will give you so much, but it's not trivial to get into.

Cheers


Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

i'd argue that a part doesnt need to have simultaneous 5 axis features to be made more efficiently on a 5 axis machine. for example, a part that we used to make on 3 axis, had some angled faces that we had to 3d surface, but on a 5 axis machine, you just tilt it to the right angle and finish it in 1 pass as a 2d contour saving a LOT of time!

IMO, anyone NOT investing into 5 axis capabilities is starting off on a backwards trajectory and higher chance of being left behind.
 

mhajicek

Active member
With the Haas rotaries on a control box, you can interface them with the machine in a couple ways. One is to have an M code send a pulse to tell the rotary to go to the next programmed position; I used to work at a shop that did that a lot. The rotary control box then sends a pulse back to tell the control it's at position. The other way is with a serial cable and DPRINT. You can DPRINT a rotary command that the rotary control will execute. We did this once for a four axis cam that required hundreds of rotary moves. I modified the Mastercam post processor to output the DPRINT lines.
 

LOTT

New member
I ran a Haas HA5C indexer off an M code from a Sharp SV-2412 like that, sending a signal then waiting for a return pulse. The Sharp is sold, I need to list the indexer for sale now that we have a machine with a true 4th.
 

LOTT

New member
And there's a member here that sells a fixture to add 5th axis indexing to a 4th fixture, can't remember his name at the moment.
 

e30ryan

New member
Do you have a resource for building macros? I have no experience with that. Is it generic G-code or is it machine specific (Mach3 vs Fadal, for example)?

A great resource is the book "Fanuc CNC Custom Macros" by Peter Smid. It is primarily for Fanuc controllers but there should be equivalent techniques for other control brands.
 

Mud

New member
@implmex
Just put the button in the work area and have the tool push the button.


I've considered having the table hit a microswitch at full travel. On a springy bracket so it couldn't be crushed.
On one machine I wired a relay to the mist coolant valve circuit, I switched from flood to mist and back to flood to trigger the Haas controller.
 

Mike1974

New member
Might have been said, but you can control a stand alone Haas rotary controller with an M code. Insert Mxx and it will index to next position, you just program the moves into the control box and the M code will activate the next rotary position. I worked at a shop that had a VF4 with 3 rotaries on it, 2 we switched the cables to run, and the 3rd (5c) was used with the separate control box.
 
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