Go Back OFN Forums > Fabrication > Race Car Fabrication

Race Car Fabrication There is a lot of cool fabriaction going on the race car industry, show us what you got.


Race Car Fabrication There is a lot of cool fabriaction going on the race car industry, show us what you got.

Reply
 
Thread Tools
  #41  
Old 11-24-2013, 12:46 PM
TheBandit's Avatar
TheBandit TheBandit is offline
Instagram @chevyhotrodder
 
Join Date: Jan 2006
Location: Ventura County CA
Posts: 4,361
A .250 depth of cut seems really deep to me. Even .200 seems really deep. When I'm roughing aluminum on my mill with a .5 dia standard 2-flute endmill I use .050 deep passes and try to finish with a cut between .010 and .015. Of course I have no idea what Im doing. I should check the machinists handbook.

Edit: after some searching I found this thread which recommends a depth of cut around 1/2 the endmill diameter, so assuming you are using a 1/2" endmill or larger, you are right in Yeh ballpark. I will have to try going deeper next time.
__________________
Clint

Sometimes you win. Sometimes you learn.

Last edited by TheBandit; 11-24-2013 at 11:27 PM.
Reply With Quote
  #42  
Old 11-25-2013, 12:30 PM
Graham08's Avatar
Graham08 Graham08 is offline
Master Fabricator
 
Join Date: May 2006
Location: Denver, NC
Posts: 1,724
Quote:
Originally Posted by TheBandit View Post
A .250 depth of cut seems really deep to me. Even .200 seems really deep. When I'm roughing aluminum on my mill with a .5 dia standard 2-flute endmill I use .050 deep passes and try to finish with a cut between .010 and .015. Of course I have no idea what Im doing. I should check the machinists handbook.

Edit: after some searching I found this thread which recommends a depth of cut around 1/2 the endmill diameter, so assuming you are using a 1/2" endmill or larger, you are right in Yeh ballpark. I will have to try going deeper next time.
I'm running a 3/4" two flute end mill to try and minimize the number of passes to do the surface. I wasn't having any chatter problems doing 0.250" cuts. I have the rotary table set up now, doing the profile work. I'll be sure to take some pictures of that process.

I use the 50% of diameter rule of thumb for end milling as a maximum since my equipment is on the light side. I also use 10% of the mill diameter for side milling. It seems like I read that in Frank Marlow's "Machine Shop Essentials"...which is a pretty good reference to have around.
Reply With Quote
  #43  
Old 11-25-2013, 04:09 PM
TheBandit's Avatar
TheBandit TheBandit is offline
Instagram @chevyhotrodder
 
Join Date: Jan 2006
Location: Ventura County CA
Posts: 4,361
Thanks Graham. That will save me some time. Not to hijack the thread too much, but sometimes I get a layered looking cut from each pass when I'm profile cutting. How do you balance vertical depth of cut with profile depth of cut? Do you engage 50% diameter down and 10% diameter over?

I'll take a look at that book reference; I'll add that to the Christmas list. I am not doing a lot of machining these days, but have plans to do more stuff in the future. I was thinking you might shave a lot of time off those arms if you did some bandsaw cuts to rough it out first.
__________________
Clint

Sometimes you win. Sometimes you learn.
Reply With Quote
  #44  
Old 11-25-2013, 04:36 PM
Graham08's Avatar
Graham08 Graham08 is offline
Master Fabricator
 
Join Date: May 2006
Location: Denver, NC
Posts: 1,724
Quote:
Originally Posted by TheBandit View Post
Thanks Graham. That will save me some time. Not to hijack the thread too much, but sometimes I get a layered looking cut from each pass when I'm profile cutting. How do you balance vertical depth of cut with profile depth of cut? Do you engage 50% diameter down and 10% diameter over?

I'll take a look at that book reference; I'll add that to the Christmas list. I am not doing a lot of machining these days, but have plans to do more stuff in the future. I was thinking you might shave a lot of time off those arms if you did some bandsaw cuts to rough it out first.
I don't think this discussion is a hijack.

What I've found works best when profiling is to leave 0.025" or so to side mill when I get finished after removing the bulk of the material with the end of the cutter. The last full depth pass takes care of the stepped look you're talking about.

Not that I'm really an expert or anything. If I had to sell these I would lose my ass, but I guess that's the price to pay for having something different than everyone else has.
Reply With Quote
  #45  
Old 12-02-2013, 12:46 PM
Graham08's Avatar
Graham08 Graham08 is offline
Master Fabricator
 
Join Date: May 2006
Location: Denver, NC
Posts: 1,724
I finally got the steering arms done. Here is a picture of my setup on the rotary table. I built a small fixture and bolted the arms to it to limit the amount of setup time. Doing this makes things a little less repeatable, but these features are mostly cosmetic, and it doesn't matter if they're off a few thousandths.



I had already cut the opening to clear the kingpin boss on the spindle when this was taken.

The next step was to take an angled cut, which determines most of the shape of the arm. I had indicated the fixture in to know where zero degrees was, which allowed me to use the rotary table to accurately set the angle of this cut.



Next was cutting a large radius to smooth things out a bit.



I had to change my setup a little bit here because the one socket head screw sticks out past the final radius, so I clamped that side of the arm over a parallel to hold it in place.

The final setup on the rotary table was the radius around the tie rod hole.



After a little filing to smooth off the corners, the finished arms look like this:





And the finished spindle/hub/brake assembly looks like this:





Reply With Quote
  #46  
Old 12-02-2013, 01:31 PM
TS3g's Avatar
TS3g TS3g is offline
Master Fabricator
 
Join Date: Oct 2008
Location: KS
Posts: 142
Very, very nice work Graham!
Reply With Quote
  #47  
Old 12-02-2013, 02:27 PM
TheBandit's Avatar
TheBandit TheBandit is offline
Instagram @chevyhotrodder
 
Join Date: Jan 2006
Location: Ventura County CA
Posts: 4,361
I would keep another couple feet between me and the wall knowing how much work it would be to replace those babies. They turned out awesome! The only critique I have is the small fillet where the tie rod clevis meets the main part of the arm. On future versions, you might consider giving that area more of a transition with a larger fillet to prevent a stress riser.
__________________
Clint

Sometimes you win. Sometimes you learn.
Reply With Quote
  #48  
Old 12-04-2013, 10:26 AM
Graham08's Avatar
Graham08 Graham08 is offline
Master Fabricator
 
Join Date: May 2006
Location: Denver, NC
Posts: 1,724
Thanks guys!

Clint,

I actually thought about using a larger ball mill to do the last cut at the bottom of the transition. As it stands, it's a 1/8" radius (1/4" end mill). If I would have a problem with cracking, I could easily go up to 1/4" radius. The reason I didn't do it this time is it would effectively be another setup because I would lose my zero in Z by changing tools.

If I only had a CNC machining center...
Reply With Quote
  #49  
Old 12-05-2013, 12:58 PM
Graham08's Avatar
Graham08 Graham08 is offline
Master Fabricator
 
Join Date: May 2006
Location: Denver, NC
Posts: 1,724
Good news is, it all bolts up!





Onto the rear suspension rework...
Reply With Quote
  #50  
Old 12-05-2013, 03:54 PM
TheBandit's Avatar
TheBandit TheBandit is offline
Instagram @chevyhotrodder
 
Join Date: Jan 2006
Location: Ventura County CA
Posts: 4,361
Awesome! Can you adjust camber or SAI with this setup?
__________________
Clint

Sometimes you win. Sometimes you learn.
Reply With Quote
  #51  
Old 12-05-2013, 05:02 PM
entropy's Avatar
entropy entropy is offline
Master Fabricator
 
Join Date: Sep 2007
Location: 95-miles from the center of Oregon.
Posts: 8,354
Quote:
Originally Posted by Graham08 View Post
Thanks guys!

Clint,

I actually thought about using a larger ball mill to do the last cut at the bottom of the transition. As it stands, it's a 1/8" radius (1/4" end mill). If I would have a problem with cracking, I could easily go up to 1/4" radius. The reason I didn't do it this time is it would effectively be another setup because I would lose my zero in Z by changing tools.

If I only had a CNC machining center...
Ok, so what you should have (easy for me to say that )done is to take say a 3/4" 2f end mill and using your radius gauge ground the square corners so the gauge fits perfectly to the OD, then grind the back clearance or relief (which in Alum. need be one angle) then you can machine the flat surface which will generate the concave radius; and using the same end mill step it up and over to generate the convex radius.
You would thus not lose the Z-zero.

E
__________________
When did empirical knowledge get replaced by a theoretical education?

Reply With Quote
  #52  
Old 12-06-2013, 08:22 AM
Graham08's Avatar
Graham08 Graham08 is offline
Master Fabricator
 
Join Date: May 2006
Location: Denver, NC
Posts: 1,724
Quote:
Originally Posted by TheBandit View Post
Awesome! Can you adjust camber or SAI with this setup?
Unfortunately, no. I could have made adjusters like I do with some supermodified stuff, but they add a bunch of weight. There is a company called Fast Axle that makes a deal that has an oversized kingpin boss and sleeves that are bored at an angle relative to outer bore, but it's probably not something you would mess with at the track because you have to pull the kingpin and take the spindle off the axle to adjust it.

Quote:
Originally Posted by entropy View Post
Ok, so what you should have (easy for me to say that )done is to take say a 3/4" 2f end mill and using your radius gauge ground the square corners so the gauge fits perfectly to the OD, then grind the back clearance or relief (which in Alum. need be one angle) then you can machine the flat surface which will generate the concave radius; and using the same end mill step it up and over to generate the convex radius.
You would thus not lose the Z-zero.

E
Thanks for the tip. I haven't ventured into grinding end mills before. I do lathe tools and drills. I guess the principles are the same, but it's just a little more intimidating. The other thing I could have done is lay the radius steps out with the larger end mill and see how much material gets missed. I think the 1/8" radius at the root will be good...I guess I'll find out soon enough.
Reply With Quote
  #53  
Old 12-06-2013, 12:43 PM
entropy's Avatar
entropy entropy is offline
Master Fabricator
 
Join Date: Sep 2007
Location: 95-miles from the center of Oregon.
Posts: 8,354
Quote:
Originally Posted by Graham08 View Post
Thanks for the tip. I haven't ventured into grinding end mills before. I do lathe tools and drills. I guess the principles are the same, but it's just a little more intimidating. The other thing I could have done is lay the radius steps out with the larger end mill and see how much material gets missed. I think the 1/8" radius at the root will be good...I guess I'll find out soon enough.
The grinding of the endmill is exactly the same as a lathe tool except you have the helix which is rather easy to sort out. Try it on a dull mill... You can do it and you will be amazed at how you use the tools and the versatility they bring to the job.

E
__________________
When did empirical knowledge get replaced by a theoretical education?

Reply With Quote
  #54  
Old 12-06-2013, 02:44 PM
TheBandit's Avatar
TheBandit TheBandit is offline
Instagram @chevyhotrodder
 
Join Date: Jan 2006
Location: Ventura County CA
Posts: 4,361
Interesting! I assume with your background all the suspension geometry on this car is being modeled and carefully designed into every component. What can be adjusted? Just caster and toe?
__________________
Clint

Sometimes you win. Sometimes you learn.
Reply With Quote
  #55  
Old 12-06-2013, 04:02 PM
Graham08's Avatar
Graham08 Graham08 is offline
Master Fabricator
 
Join Date: May 2006
Location: Denver, NC
Posts: 1,724
Quote:
Originally Posted by TheBandit View Post
Interesting! I assume with your background all the suspension geometry on this car is being modeled and carefully designed into every component. What can be adjusted? Just caster and toe?
Well...yes and no. Carefully designed, but not necessarily modeled. The front is pretty simple because there isn't a whole lot you can do with the solid axle/3 link combination. On the geometry side, my primary concerns were making the links as long as practical, making sure there was a significant amount of Ackermann geometry, and having a slight rising rate on the rockers to make sure they can't go over center. But, it's all a compromise to make sure lightness and stiffness are taken care of also.

Last summer I helped a friend for a few races and did some analysis...and I learned that roll center heights are a big deal from a load transfer perspective, so that's why I added the serrated adjuster for the Panhard rod.

In terms of geometry adjustments, there is total caster, toe, and roll center height in the front. You can adjust camber a bit through front stagger...Hoosier makes two different front tire constructions for each side, so you can get anywhere from zero to about 6" of rollout difference depending on which ones get paired up. Anything else (like caster split) requires a new axle. KPI changes would mean custom spindles. These are "standard" 10 degree spindles...I've heard of 4, 5, and 6 degree versions, but they're not as common.

I'm just hoping it all works!

On Edit: Almost forgot scrub radius! Tried to minimize it to make manual steering work.

Last edited by Graham08; 12-06-2013 at 04:10 PM.
Reply With Quote
  #56  
Old 12-06-2013, 08:12 PM
deaner's Avatar
deaner deaner is offline
Master Fabricator
 
Join Date: Jan 2013
Location: Northern Ohio
Posts: 436
You mentioned Ackermann. How much drifting do pavement sprints do? Dirt cars are always "turning" right as the car turns left so Ackermann just makes for drag as one wheel is toeing out.
Reply With Quote
  #57  
Old 12-06-2013, 11:06 PM
Graham08's Avatar
Graham08 Graham08 is offline
Master Fabricator
 
Join Date: May 2006
Location: Denver, NC
Posts: 1,724
Quote:
Originally Posted by deaner View Post
You mentioned Ackermann. How much drifting do pavement sprints do? Dirt cars are always "turning" right as the car turns left so Ackermann just makes for drag as one wheel is toeing out.
Pavement cars aren't as sideways as dirt cars, but have fairly decent yaw angles.

My theory on running a lot of Ackermann has as much to do with keeping heat in LF tire as anything. You're right that it scrubs the inside tire but that scrub puts heat in the LF and keeps the garbage cleaned off it so it can actually do something. If I was running a heavier car on a large banked track I would be looking at running anti-Ackermann because generally that's where the pair of tires would make the most grip.

Reply With Quote
  #58  
Old 12-06-2013, 11:22 PM
deaner's Avatar
deaner deaner is offline
Master Fabricator
 
Join Date: Jan 2013
Location: Northern Ohio
Posts: 436
Ah, makes sense, LF prolly isn't fully on the ground when turning to the right anyway. Great build btw.
Reply With Quote
  #59  
Old 12-10-2013, 02:44 PM
argonsniffer's Avatar
argonsniffer argonsniffer is offline
Master Fabricator
 
Join Date: May 2009
Location: rainy-miserable-UK
Posts: 209
Nice work on this.. REAL nice work....
Reply With Quote
  #60  
Old 03-18-2014, 05:01 PM
Graham08's Avatar
Graham08 Graham08 is offline
Master Fabricator
 
Join Date: May 2006
Location: Denver, NC
Posts: 1,724
Finally getting back to this after some customer projects and a back injury that made me pretty useless for a bit.

I'm about to start making chips fly on the Watt's link center pivot for the rear suspension.

One thing that making the steering arms and caliper brackets made painfully obvious was that I needed a better vise. I've been using a couple poor Chinese copies of D40 Kurts that came with the machine. Enco ran a sale a while back for 15% off anything plus free shipping, so I finally pulled the trigger on a new D688 Kurt. What a difference!

I got the to-do list down to the point that I had a few minutes to tram the mill and mount the new vise to it. The vise I had been using was warped about 0.002" on the fixed jaw. The new Kurt is straight as close as I can measure. Here's a pic:



I probably added 50% to the value of the machine by putting a Kurt on it, but I figure if I ever upgrade the milling machine, the Kurt will stay with me, and I'll give the cheapo's to the next owner.

More parts coming soon...
Reply With Quote
Reply

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 02:34 PM.

Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Template-Modifications by TMS
Copyright 2012, Offroad Fabrication Network