440....is it worthy? or 770?
Hi guys,
well right now the 440 is about $3k cheaper with the sale ( no sale on the 770). this is about 35% less cost then the 770.
I am just going with a basic package and will build my own stand/enclosure etc. Obviously the better value is with the 440, but of course the 770 is a better machine.
Would a 440 be able to take a .010 depth of cut with a boring head or end mill in stainless? these cuts will be on the ID of stainless pipe and need to go into the pipe about 1.5". I was hoping to use an end mill going in a circular pattern working down the ID of the pipe. hoping to stay away from flood coolant for now. fog buster OK.
I know the 770 is better all abound, but its also quite a bit more money. If the 440 can handle a little stainless then it should do the trick?
TIA.
Re: 440....is it worthy? or 770?
Quote:
Originally Posted by
cleanz
Hi guys,
well right now the 440 is about $3k cheaper with the sale ( no sale on the 770). this is about 35% less cost then the 770.
I am just going with a basic package and will build my own stand/enclosure etc. Obviously the better value is with the 440, but of course the 770 is a better machine.
Would a 440 be able to take a .010 depth of cut with a boring head or end mill in stainless? these cuts will be on the ID of stainless pipe and need to go into the pipe about 1.5". I was hoping to use an end mill going in a circular pattern working down the ID of the pipe. hoping to stay away from flood coolant for now. fog buster OK.
I know the 770 is better all abound, but its also quite a bit more money. If the 440 can handle a little stainless then it should do the trick?
TIA.
You need to look at the working area for Z height between the 440 and 770 and see if you can get the boring bar in the 440 and clear your workpiece. The 770 is a lot more machine (in comparison). So don't nickle and dime yourself out of what you need for the job. If it's marginal, don't buy marginal.
1.5" of flute stickout on a standard end mill on any Tormach is a lot and might give you major problems in stainless. You may want to look at insert cutters to work your way down the pipe or maybe a high feed low engagement cutter like or similar to the Tormach Dijet. It won't be big cuts but it will be reliable fast low z depth passes with small hp requirements and no big rigidity problems.
Re: 440....is it worthy? or 770?
the 440's are quite capable little machines . I haven't used a boring head on mine yet but I'd have confidence they could easily do the job if needed . Best thing to do is calculate your clearances , machine travel vs vise height , bore head length etc .
There's a concept that bigger is always better but it's not necessarily the case .
Re: 440....is it worthy? or 770?
Another option to consider is mounting the tube horizontally and running the boring head on a right angle drive. This nicely solves the Z-axis clearance problem. A used Bridgeport compatible right-angle drive works well on a 770 but I haven't checked the spindle diameter on the 440 so no idea if something similar might be done with the 440. If you feel up to rolling your own I've seen right angle drives based on gears from a vehicle differential.
Re: 440....is it worthy? or 770?
Yes, the motor on the 440 is strong enough for that cut, at least if you use the lower-RPM belt setting.
I regularly full-slot 303 (which, admittedly, is easy, as far as stainless goes.) with quater inch end mills (although I do take just 1/8" at a time in that case.)
There's some question about workholding -- how large is the pipe? How will you fit it all in the throat / nose-to-table space?
Re: 440....is it worthy? or 770?
Quote:
Originally Posted by
jwatte
Yes, the motor on the 440 is strong enough for that cut, at least if you use the lower-RPM belt setting.
I regularly full-slot 303 (which, admittedly, is easy, as far as stainless goes.) with quater inch end mills (although I do take just 1/8" at a time in that case.)
There's some question about workholding -- how large is the pipe? How will you fit it all in the throat / nose-to-table space?
@jwatte
the pipe is 1" OD - ID is about .910 ish. I just need to take .010 - .015 out of the ID to give it a bright shiny finish. no Critical ID size needed - just a good finish. I could even take it in two passes if necessary. I was going to make some fixture plates that could be 6-8" long x 1.5 - 2 wide with say 4-6 1" holes in each. the holes would have a small step at the bottom for the pipes to bottom out on.The holes could be .250 shorter then the pipes sticking out. There would be a brass set screw in each hole from the side to secure the pipes.
I could then go down the pipe in a circular motion with the shear hog or mini-shear etc. I think it would work quite well.
do you think the 440 could machines thoes 1" holes in the steel fixture plates? I would need to make them on the 440. Could use a 1/4 or 3/8s end mill? Im ok with very slow feed rates to get thoes holes. i would only need to make them once.
Re: 440....is it worthy? or 770?
Re: 440....is it worthy? or 770?
Your feed rates should not be too slow, that will cause rubbing and other bad stuff.
Instead, the main thing you back off on is depth of cut / width of cut.
The 440 can mill any material, pretty much, as long as you take it easy on DoC / WoC.
Although, TBF, when I do titanium, I use 3/16, not 1/4 or 3/8 -- I save the bigger ones for more free-cutting materials.
The only question is: how long are the pipes? Maximum size from table to tip-of-tool for a 1/4" end mill with 1" flutes for me is about 9 inches (when placed in TTS ER20 tool holder, an in the spindle.) You could probably get 1-2 more inches if you used R8 tool holding, but changing and zeroing those tools is a major PITA for each tool change.
If they're napkin rings, or TP holders, or something, that's a few inches long, then this will work fine.
Re: 440....is it worthy? or 770?
The only reason I would get a 440 is if I didn’t have room for a bigger machine. Find some other way to save money - eBay tool holders, make your own coolant pump, skip the expensive probes, shower curtain enclosure, etc. I bought a 770 and I still run out of room for set ups. Also, I hear about fewer 770 than 440 problems on forums, and I bet there are more 770s out there since they’ve been sold longer.
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