Mills and Lathes

link1896

Mr Greenfield
Bleed ports both ends? That makes life easy.

I recall some great fun from someone missing the small detail of bleed port at the top on a custom build.
 

beeb

Dr. Beebenson, PhD HA, ST, Offset (hons)
My mechanic mate picked up two sets of 4 piston wilwood calipers for under $1k for the Escort van, to suit vented fronts and solid rears. Time to work out how to make them fit and with which rotors...

It is running 5x114.3 stud pattern (rear diff is from a hilux, engine is SR20) front rotors are from an EA or EB (?) falcon were the right size, just 1mm narrower. A quick dry fit on the car showed it was doable and either a truncated angle or machined block would work. Quick look out the back and some 75x25 6061 aluminium bar was found.

The bits:


How it is meant to look.


Having learned my lesson I face off the bar all round to get nice flat surfaces before I start machining the important bits.


The caliper bolts were in line with the strut mounts so a little machining was in order to recess the plates to suit.


Blanks machined to size and ready for the next step.


A closer look at the recess.


The blanks were trimmed and then relieved to fit the pistons, Initially I was going to have to make space around the abs body for the hub. I thought about using a 4" hole saw and a bit of a tidy up but then discovered those aren't the final hubs so this was ok.


And does it all work? spacers holding the bracket up and a convenient drill bit holding it out where it needs to be.


Yes it does. I will redo calcs as it looks a bit skinny but there is plenty of meat left to bolt it all together, the flat area is 14mm thick and the bosses for the radial caliper mounts are 18x23x21. I am thinking those will be studs so that the tapped holes in the bracket don't get worn out.

Final test fit on the car next week and off to Bunnings for some tapped holes.
Ah, the old IS to post type mount adapter. Nice one.
 

Dales Cannon

lightbrain about 4pm
Staff member
I wanted to use Wilwood calipers on #2's escort but the cost was crazy and we picked up the R33 ali 4 pots for $100. These are much lighter and they are a great product.
 

komdotkom

Likes Bikes and Dirt
I wanted to use Wilwood calipers on #2's escort but the cost was crazy and we picked up the R33 ali 4 pots for $100. These are much lighter and they are a great product.
And with 4x40mm pistons you'll have more stopping power than the Wilwoods, less flex and dust boots on the pistons. I've got a few oem caliper rebuild kits for the Skyline calipers in the shed somewhere if you need them, I swapped to a much bigger rotor/caliper on my gtr
 

Dales Cannon

lightbrain about 4pm
Staff member
Bugger, we bought rebuild kits... ah well. The escort only weighs 800kg or something so brakes will be overkill with 300/270mm rotors.
 

SummitFever

Eats Squid
Turners cubes are very cool.


Time to make the steady rest for the lathe if I’m going to make the burnishing tool


ITEM extrusion, 4 deep groove ball bearings.


Should be fun. Not sure if you know this, so hopefully I'm not teaching you to suck eggs. To hit an accurate final diameter on a lathe is a bit counter intuitive. You might be tempted to get close to the desired diameter and then take a series of ever finer passes to 'hone' in on the desired diameter. Don't do this.

Ideally, you want to hit the final diameter by taking 3-4 passes of almost identical cut depths (but a proper depth of cut, not some sort of rubbing pass). What depth of cut you take is dependent on the material, the cutter, the feedrate and your machine.

Do a bunch of test cuts and see what depth of cut and feedrate your lathe is most happy with and what gives the desired surface finish. Once you know this depth then rough machine the part down to within 4 passes of this cut depth.

Do the first pass and mic the result. Adjust the next pass based on the result and re mic. Repeat that step again and you will now be on the last pass that will hit the desired OD but with the knowledge of what sort of compensation you need to dial in to get from A to B. Apply that knowledge to get the last pass exactly right. Set your dials accordingly, engage the power feed and bask in the glory of that final cut that results in the spot on diameter.

Hope this makes sense. Might make more sense with some numbers. Say you arrive at a depth of cut of 0.5mm as the 'ideal' cut depth for your combo of cutter and material. Touch off on the workpiece, zero you dial and then dial up 0.5mm. Do the cut and measure. The result is 0.48mm. You need to dial in an extra 0.02mm to get an actual cut of 0.5mm. Dial in 0.54mm on the next cut. You should now be bang on 1mm off. Cut and measure. See if you're +0.02 comp is working. Use the results to make the final cut.

This approach will get good results even if your machine is flogged out, flexy or the dials are a bit inaccurate.
 

Dales Cannon

lightbrain about 4pm
Staff member
Should be fun. Not sure if you know this, so hopefully I'm not teaching you to suck eggs. To hit an accurate final diameter on a lathe is a bit counter intuitive. You might be tempted to get close to the desired diameter and then take a series of ever finer passes to 'hone' in on the desired diameter. Don't do this.

Ideally, you want to hit the final diameter by taking 3-4 passes of almost identical cut depths (but a proper depth of cut, not some sort of rubbing pass). What depth of cut you take is dependent on the material, the cutter, the feedrate and your machine.

Do a bunch of test cuts and see what depth of cut and feedrate your lathe is most happy with and what gives the desired surface finish. Once you know this depth then rough machine the part down to within 4 passes of this cut depth.

Do the first pass and mic the result. Adjust the next pass based on the result and re mic. Repeat that step again and you will now be on the last pass that will hit the desired OD but with the knowledge of what sort of compensation you need to dial in to get from A to B. Apply that knowledge to get the last pass exactly right. Set your dials accordingly, engage the power feed and bask in the glory of that final cut that results in the spot on diameter.

Hope this makes sense. Might make more sense with some numbers. Say you arrive at a depth of cut of 0.5mm as the 'ideal' cut depth for your combo of cutter and material. Touch off on the workpiece, zero you dial and then dial up 0.5mm. Do the cut and measure. The result is 0.48mm. You need to dial in an extra 0.02mm to get an actual cut of 0.5mm. Dial in 0.54mm on the next cut. You should now be bang on 1mm off. Cut and measure. See if you're +0.02 comp is working. Use the results to make the final cut.

This approach will get good results even if your machine is flogged out, flexy or the dials are a bit inaccurate.
I used to do this (mini cuts) on my flogged out old mini lathe. It sort of worked but was tedious and definitely not reliable. The new lathe is easy, dial it in and cut... helps to have the dro. Must fit one to the mill.
 

link1896

Mr Greenfield
I’m using dial indicators on noga arms, in the tail stock chuck, and off the bed. One to measure tool movement, other to measure work piece directly. Can reconfigure depending on which direction I want to measure tool movement.

White board next to me, measured current diameter and target.

(Current - target )/2= tool movement in X direction.

My last pass, to achieve final diameter, I set the tool position with the motor off so there is no vibration.


Works for me. I can achieve typically +0.01 to 0.02mm tolerance in ally.
 
Last edited:

kten

understands stuff moorey doesn't
I’m using dial indicators on noga arms, in the tail stock chuck, and off the bed. One to measure tool movement, other to measure work piece directly. Can reconfigure depending on which direction I want to measure tool movement.

White board next to me, measured current diameter and target.

(Current - target )/2= tool movement in X direction.

My last pass, to achieve final diameter, I set the tool position with the motor off so there is no vibration.


Works for me. I can achieve typically +0.01 to 0.002mm tolerance in ally.
Tight tolerance. My first trade was as a machinist, never worked in metric so had to google it and convert to inches lol
 

Dales Cannon

lightbrain about 4pm
Staff member
Yeah, Northern Ireland didn't move with the times :rolleyes: plus I was working for a merican company
A mate is a tool maker by trade and he uses a combination of both! microns and thou. My only experience doing work on a job in the USA nearly ended in disaster when I sized up the cranage for US tons instead of metric tonnes. The lift allowances are different so it wasn't immediately obvious but when I came up with a 600t crawler when we were using a 750t crawler here the penny dropped. Or was that a dime. I had an argument with one of the older dinosaurs who was espousing the benefits of imperial over metric (hint, there are none) and I said you can't even do it properly, weight in pounds not stone, a ton is 240 pounds short of a proper ton etc etc. I called him a base 10 failure after that.
 
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