[vandal968]

I've got a little Emco injection molder, the handle is broken. I've drawn it up in CAD and want to cnc machine a replacement. The first side is easy (if slow), the second side is tricky from a fixturing standpoint. If I were making 100 of them, I'd make some elaborate fixture to hold them for doing the second side. I only need one. How would you guys do it? The handle is about 9" across its widest points.



thanks for any pointers,
v

[mfgbydesign]

or Carr Lane. If they don't have one to fit or modify,
1. Make a hub. Drill & tap the handle holes at the angle you want, or make the hub longer & go in at a right angle.
2. Make the handles on a lathe or buy them threaded on the end.
3. Screw it together.

[vandal968]

Good advice, but I want to cnc this thing. It's an excuse to try meshcam, and I want the replacement part to be a 100% match for the original piece (except cnc'd rather than cast).

So, how would you fixture for the second side?

cheers,
v

[fizzissist]

Potting epoxy in an aluminum base that you can tap for clamping. Machine one side complete, flip it over and fixture in this one to finish the other side, sand and polish the blend.

Alternately, to do the handle sections one at a time, make an angle fixture that the base will screw into exposing the lug, then use a radius'd slotting cutter and machine around the form.

The blank could be simple thick plate, routed to the outermost dimension, then finished as above.

[mfgbydesign]

I'm not trying to be smart here, but I frequently look at things in reverse order for a reason. My 2 cents without too much thought:
1. Rough the handle side. Leave square ends for vise. Maybe extend the center shaft & leave square for removal later (protrusion).
2. Rough machine side.
3. Finish Machine side except leave square around boss.
4. Finish handle side. Leave protrusion bigger than knobs.
5. Finish machine side, locating on protrusion.
6. Remove protrusion.

[Delw]

easy lay it down flat
surface everything just below centerline. then make vise jaws holding on the flats of the hub and profile knobs. clamp down surface everything. do knobs first as once you his center line it wont have any on those. but you will have pleanty of contact to hold while surfacing. no rghing all finish.

if need be have a small .125 flat on the round parts for location who cares what it looks like.

personally I would make a hub then buy some balls from mc master car then all thread them in, but thats me and about 20 mins worth of free time.

finished

[RomanLini]

If the hub has one main female thread (on the bottom) you could make a side fixture and a bolt into that thread to hold the item.

Then for machining the two sides you only need to constrain rotation (around the bolt) so any simple fixture that stops it rotating would suffice. (Like some packing under the 2 balls would allow the second side to be machined.)

[vandal968]

It does, in fact, have a big female thread in the bottom (3/4-10). That's an excellent idea for fixturing it, and I'm going to try it that way. It hadn't occurred to me since I was going to make the threaded hole last. I'm glad I asked the question.

Thanks to all who offered advice.

cheers,
c

[Kevin45]

I've got a little Emco injection molder, the handle is broken. I've drawn it up in CAD and want to cnc machine a replacement. The first side is easy (if slow), the second side is tricky from a fixturing standpoint. If I were making 100 of them, I'd make some elaborate fixture to hold them for doing the second side. I only need one. How would you guys do it? The handle is about 9" across its widest points.



thanks for any pointers,
v

I am assuming that you are making this out of a piece of thick flat stock. I would take a square piece of stock 9" wide and a little thicker than what is needed. Square the stock up all four sides. Then I would machine either the bottom bung and a portion of the handle ears, clamp on those then machine the remaining portion if you want the part to stand up while machining.

Or machine two bungs, clamp on the ends in a vice, machine one side of the handle down to centerline of the flat plate, flip over then machine the same profile down to centerline. You can then stand it up and machine off the bung between the handle ears, flip it over and machine the other bung down to the length required. Add construction holes as needed for pickup center points.

Personally I would prefer to do it the second way. One program to run both sides, by mirror imaging, flip part and machine using same program.