CAM setup for the flange plate

I have a couple of these end mills from SGS Tool (now branded as Kyocera SGS). Called "V-Carb 55SS Short", aka "Series 55":

They are recommended for steels, stainless steels, cast iron and high temp alloys, so should be good for my 304 stainless flange. And furthermore, they both appear to be in decent condition ie not buggered or chipped.

The reason for looking them up is to get the recommended cutting feeds and speeds:

For profile cutting with an 8mm cutter (2nd column), it looks like 3090rpm; for HSM (adaptive), 4665rpm and feed rate 26um per tooth (profile); 51um per tooth (HSM).

Double check that I understand correctly:

• 51um feed per tooth for 5 flute cutter at 4665rpm >> 1194 mm/min
• 26um feed per tooth for 5 flute cutter at 3090rpm >> 396 mm/min

Yes, that computes correctly. 

I don't understand this bit:

Ah:

So it means "keep Ap below 12mm for profile and 16mm for HSM" and "keep Ae below 2mm for profile and 0.4mm for HSM". It's difficult to see how I could keep Ae below 8mm when machining a slot. I guess this means that it's only intended for finishing, not roughing. Ooof yes:

So, possibly not the ideal choice here. What else have I got? I have some V7 INOX cutters from YG in 8mm with 0.5mm nose radius and necked shank with flat (Weldon) shank, p/n EME32906-1. Those are a bit exotic for this application but at least they are rated "excellent" for stainless steels including 300 series.

The data wasn't easy to find but it's held on a Hungarian YG site.

Here's the feeds and speeds table:

For 300 series SS, they recommend 3820rpm, 435 mm/min, Vc = 95 m/min and 28um per tooth. Again, sanity checking gives:

• 3820rpm x 28um x 4 flutes >> 427 mm/min. 
• And the surface speed resulting from 3820rpm and an 8mm cutter >> 96 m/min.

So that all checks out. Finally, for slotting, the depth should not exceed the cutter diameter. But I intend to limit the stepdown to around 2.4mm (30%), as the part will be hanging out over the end of the vice and will only be held on by a few tabs on the last pass.

Looks like a deal. I will dial those numbers back a bit, perhaps 15um per tooth (230 mm/min) and 3000rpm. With some stainless steels, running lower speeds and lighter cuts can cause work hardening but hopefully that won't be an issue here with a fairly modest reduction in F&S.

I'll also have to fill the coolant system again. It got a bit smelly, so I emptied and rinsed it out a few months ago.

Automated flange probing using CHIPS?

Flange probing? Fnaaaarrrr!

But seriously, rather than manually position the probe at each of the 8 bores / holes, I guess I could create gcode to do this for me, saving the coordinates to a log file (CHIPS does this automatically). Then I could take the coordinates from the log file and update or create a sketch from them.

Or rather, I could get Mr AI to generate the file for me. I told it to use the CHIPS probing functions within CNC12 and take my coordinates of the approximate hole centres as starting positions. This is what he / it came up with. I've removed a load of blank lines to make it 

(===================================================================)
(       AUTOMATED FLANGE PROBING ROUTINE VIA CHIPS ADD-IN          )
(===================================================================)
( Clears offsets, rapids to approx holes, probes via CHIPS P9114,  )
( and logs True X, True Y, and Dia into probe_cycle_history.xml    )
(===================================================================)
G21 (Metric Mode - Change to G20 if your dimensions are in Inches)
G90 G54
T99 M6 (Load Touch Probe - Adjust tool number to match your carousel)
(----------------------- CONFIGURATION VARIABLES -------------------)
#501 = -6.0    (Z-Depth: How deep inside the holes the probe will trip)
#502 = 38.0    (Nominal Diameter of the 4 Main Bores)
#503 = 10.0    (Nominal Diameter of the 4 Bolt Holes)
(----------------------- [USER INPUT] APPROX CENTERS ---------------)
(--- 4 Large Main Bores ---)a bit more compact.
#10 = 0.000    (Bore 1 Approx X)
#11 = 0.000    (Bore 1 Approx Y)
#20 = 0.000    (Bore 2 Approx X)
#21 = 0.000    (Bore 2 Approx Y)
#30 = 0.000    (Bore 3 Approx X)
#31 = 0.000    (Bore 3 Approx Y)
#40 = 0.000    (Bore 4 Approx X)
#41 = 0.000    (Bore 4 Approx Y)
(--- 4 Small Bolt Holes ---)
#50 = 0.000    (Bolt 1 Approx X)
#51 = 0.000    (Bolt 1 Approx Y)
#60 = 0.000    (Bolt 2 Approx X)
#61 = 0.000    (Bolt 2 Approx Y)
#70 = 0.000    (Bolt 3 Approx X)
#71 = 0.000    (Bolt 3 Approx Y)
#80 = 0.000    (Bolt 4 Approx X)
#81 = 0.000    (Bolt 4 Approx Y)
(===================================================================)
(                     PROBING SEQUENCE START                        )
(===================================================================)
G43 H99 Z15.0   (Apply tool height offset, move to safe clearance Z)
(--- PROBE BORE 1 ---)
G00 X#10 Y#11       (Rapid to approx center)
G01 Z#501 F1000     (Feed smoothly down into hole)
G65 P9114 D#502     (CHIPS Bore Cycle: Appends data to history XML)
G00 Z15.0           (Retract out of hole safely)
(--- PROBE BORE 2 ---)
G00 X#20 Y#21       (Rapid to approx center)
G01 Z#501 F1000     (Feed down)
G65 P9114 D#502     (CHIPS Bore Cycle)
G00 Z15.0           (Retract)
(--- PROBE BORE 3 ---)
G00 X#30 Y#31       (Rapid to approx center)
G01 Z#501 F1000     (Feed down)
G65 P9114 D#502     (CHIPS Bore Cycle)
G00 Z15.0           (Retract)
(--- PROBE BORE 4 ---)
G00 X#40 Y#41       (Rapid to approx center)
G01 Z#501 F1000     (Feed down)
G65 P9114 D#502     (CHIPS Bore Cycle)
G00 Z15.0           (Retract)
(--- PROBE BOLT HOLE 1 ---)
G00 X#50 Y#51       (Rapid to approx center)
G01 Z#501 F1000     (Feed down)
G65 P9114 D#503     (CHIPS Bore Cycle)
G00 Z15.0           (Retract)
(--- PROBE BOLT HOLE 2 ---)
G00 X#60 Y#61       (Rapid to approx center)
G01 Z#501 F1000     (Feed down)
G65 P9114 D#503     (CHIPS Bore Cycle)
G00 Z15.0           (Retract)
(--- PROBE BOLT HOLE 3 ---)
G00 X#70 Y#71       (Rapid to approx center)
G01 Z#501 F1000     (Feed down)
G65 P9114 D#503     (CHIPS Bore Cycle)
G00 Z15.0           (Retract)
(--- PROBE BOLT HOLE 4 ---)
G00 X#80 Y#81       (Rapid to approx center)
G01 Z#501 F1000     (Feed down)
G65 P9114 D#503     (CHIPS Bore Cycle)
G00 Z50.0 M05       (Clear part completely, stop spindle)
M30 (End of Program)

But no. In the end it bearly seemed worthwhile. I'd have to determine the approx hole centres and also manually transcribe the output (ie accurate / actual hole centres), no matter what.

So no, I couldn't be arsed to go this route. Instead I just used the CHIPS boring macro to acquire the coordinates and entered them directly into the Fusion sketch. But it looked plausible.

Probing the exhaust manifold flange bore positions using CHIPS and Renishaw touch probe

I haven't checked the setup of the Renishaw probe for some time now. Any eccentricity (runout?) of the probe tip will lead to errors in the measured bore coordinates. The eccentricity is measured using a mechanical DTI with very low tip force - obvs you don't want the probe tip to move before the DTI moves. We are trying to measure the runout of the probe as you rotate it 360 degrees. For this, you need to remove the electrical connecting cable.

This Baty DTI resolves 10um, which is fine for my machine, as I will be doing well to achieve much better accuracy than 10um. Or even to get close to 10um to begin with, after careful setup.

The eccentricity is corrected by tightening and loosening the 4 bolts holding the body to the arbor. There's a steel ball bearing that acts as a pivot. I managed to get the runout well below 10um, like 2-3um ie barely registering.

Also measured the diameter of the ruby tip. This has a nominal diameter of 6mm and measures at 5.985 using a 1um micrometer.

Using an old HST bearing as a precision ring gauge, I can check the calibration of the probe as it stands. This is almost convincing - an error of around 12um.

Then I ran the "tip map" function, which plots the measured radius at different angular positions around the ring gauge:

This was before adjusting the probe runout

I managed to get this output at one stage. No idea how this happened, as it's clearly bollocks. If only!!

And this was the final result.

Better check the flange is reasonably horizontal:

Then I started probing the bores, setting my origin at the centre of the first one.

2nd hole:

3rd hole:

4th hole:

Then on to the bolt holes. These are M8 threaded (6.8mm tapping drill) with a 6mm probe, so very little room around the 6mm probe tip.

1st bolt hole:

2nd bolt hole:

3rd hole:

4th bolt hole:

All done. Now what angle is the flange plate at?

This is the angle to the Y axis. If the measured angle was zero, the probed face would be dead parallel to the Y axis.

Here are the various bores and holes drawn up in a sketch:

Extruded, looks like this. The bolt holes for this side of the flange connection are 9mm (M8 clear).

And after some CAM and toolpath setup, I have some gcode ready to go.

The 2D drawing shows the extents of the model that need to be accommodated withing the 100 x 10mm stock.

Reassembling the TB-3 tube bender and trying it out again

This machine seems to be badged as a "tube bender TB-3". Looks to be of Chinese origin, but no doubt there will be US suppliers (I bought this in Canada) who claim it was "made" (ie packed and shipped) in the USA. 

Note that a "tube" is defined by its outside diameter, whereas a "pipe" is defined by its internal diameter. For a pipe/tube bender, this is important, since the formers / dies are tailored to a specific diameter. Here we are talking about exhaust tubes.

The original supplier (Woodward Fab, as identified by the stickers on the product) is still in business. However, they seem to have blocked access to their site from where I'm sitting. Presumably you have to be in their local (USA) market to be allowed in. There's some irony there, given that they are almost certainly passing off generic Chinese products as their own, domestically produced items. Call me a cynic.

However, and perhaps rather bizarrely (not), the apparently exact same product is available from a wide range of suppliers. Here's one such that is based in the UK. It seems that a new example with 3 sets of dies comes in around £1000 including vat.

The Chinese packing box is visible in the background. I don't have a problem with that. Note that these boys (W Neal Services Ltd) don't claim they are made in the UK.

Instructions seem to be a little harder to find, although you might argue they are hardly neccessary. Either way, here's a set of instructions and a parts list from one of the Chinese manufacturers.

SPECIFICATIONS
Model:	TB3
Maximum Machine Capacity:	2” (50.8mm) Capacity Mild Steel*
Dies Included (x 3):	1” (25.4mm) Diameter x  3” Radius x 120˚
	1 ½” (38.1mm) Diameter x 5” Radius x 120˚
	1 ¾” (44.5mm) Diameter x  6” Radius x 120˚
Die Centre Hole:	25mm Diameter
Pin Holes:	22mm Diameter
Maximum Bending Angle:	240°
Handle Length:	900mm
Dimensions – machine (apx):	1000mm x 600mm x 1080mm (l x w x h)
Dimensions – packaging (apx):	1200mm x 500mm x 520mm (l x w x h)
Weights – net/gross (apx):	64Kg/67Kg

Note that the factory supplied die sets have a bend radius that is largely proportional to the tube diameter. That's fair enough. The reason mine are all the same bend radius is because I had to make my own dies up from a short length of steel that ended up being cut into 3 sectors of 120 degrees. I was buggered if I was going to machine the sectors down further - manually machining the circular grooves nearly killed me as it was.

I found these photos of the fabrication:

Let's get it assembled and ready for action:

The sector rotates with the swinging arm. The fixed part of the die set is anchored to the main frame. You can see that this fixed guide needs to be at 90 degrees to the main frame (like this) when a tube is installed and ready to go. I don't have a piece long enough to show that (yet), although that should change any minute now......

Hmmf. Finally I received the 304 stainless tubes. I ordered these on Wednesday with "next (working) day" delivery. However, they didn't ship them until Thursday evening (aka Friday in terms of working days) and of course the courier doesn't deliver over the weekend. So that's essentially a 4 or 5 calendar day turnaround, depending how you look at it. Not massively overimpressed. Usually metals4u ship promptly and I've timed my orders to avoid the weekend in the past.

And also I received some Chinesium expanding wall bolts (M12 bolts) to hold the frame down to the floor. Allowing this thing to tip over could give you a nasty bit of pain, weighing ~65kg as it does.

I've made some concrete worm holes using an SDS+ drill and a 20mm masonry drill. Luckily no steel mesh was found on the way in.

I preset the bolts using the impact driver and some cast washers.

There. I reckon 2 will suffice. Seems pretty solid.

As well as the 32mm and 38mm tubing, I got a 360mm length of 10x100mm 304 flat bar. This should be sufficient for at least 2 good flange plates, even allowing for some waste for clamping etc.

I also need a level extension for operating the bender. I previously bought some 2" thick wall tube when I was making a drawbar for the Tree lathe. It wasn't much cheaper to buy a shorter length, so I ended up with 3m of the stuff, cut into 3 lengths. One such length is still slightly too long so needed to be reduced a bit.

And let's see what happens.

That wasn't too bad - and certainly easier than when I used the machine on that thick tubing I got previously (~2.5mm wall thickness). Of course, it wants to swipe the tube across the bench and clear everything onto the floor. But I had to choose an orientation and this seemed like the best compromise, given that I also need to be able to swing the long handle, keeping my elbows clear of any hard, fixed objects.

This is the characteristic squashing of the inside radius that you get when bending thin wall tubing without an internal mandrel:

There's a bit of a crease where the end of the sector meets the tube:

Here's the outside of the bend.

That's fine really and pretty much as expected. I will be using Chinesium mandrel bends to fabricate the more intricate and tight bends, so the bender will only be used for the more gentle bends. 

Note that there is a minimum length that needs to engage with the fixed guide. I managed to pull the tube past the outboard end of the guide and this is what happens. No damage done but it's good to be able to characterise the behaviour in terms of what "lost lengths" I need to expect:

Looks like about 65mm from the end of the bend:

You can see where the welded seam is located here. Perhaps there's an ideal position to locate the seam when setting up a tube for bending.

Now I will await the arrival of my mandrel bends from China. These are a selection of 45 and 90 degree bends in 32mm 304 1.5mm tube. Currently they appear to be waiting departure at the airport, somewhere in China.

In the meantime, perhaps I will get on and prepare to machine a couple of those flange plates. It's been a while since I use The Shiz (or in fact any of the CNC machines), so it will be good to blow off some of the cobwebs and make some chips.....