Bladed ARB Lever Arms-Manufacture

[David Goodwin]

Hi all,

This year our suspension team decided to design a bladed lever arm system for our ARB's. The designs are all finalised, and waiting to be manufactured. The workshop noted that the lever arms would be difficult to make due to the tapering width and that vibration of the arms during manufacture may or would be an issue.

Has anyone else who has manufactured this style of lever arms had these problems? If so, how did you overcome this vibration issue?

If no teams have any experience in manufacturing these arms, is there any recommendations that any of you manufacturing experts can make in overcoming this issue?

Cheers, David

[David Goodwin]

Hi all,

This year our suspension team decided to design a bladed lever arm system for our ARB's. The designs are all finalised, and waiting to be manufactured. The workshop noted that the lever arms would be difficult to make due to the tapering width and that vibration of the arms during manufacture may or would be an issue.

Has anyone else who has manufactured this style of lever arms had these problems? If so, how did you overcome this vibration issue?

If no teams have any experience in manufacturing these arms, is there any recommendations that any of you manufacturing experts can make in overcoming this issue?

Cheers, David

[Jersey Tom]

Kinda depends specifically on what your design is.

Thin sections are a bitch for tool chatter. It may involve a couple fixtures, but big deal.

Can turn the thing on a lathe to get the tapered bit first.

Then clamp it pretty securely on a mill, and mill off one side of the cutoff (half of what makes your thin center section).

Flip it, and you'll have to have some backing piece on your fixture to support the center section while you mill the other side.

E-zay. Unless your design prohibits that.

[Chapo]

When i was doing some work in the shop last year i was discussing how to make some really thin stuff and one of methods that we worked discussed was imbedding things in wax. Pretty much make up a hollow jig to mount the blade in and then fill it up with a fairly hard but not brittle wax. Just machine as normal, the wax should absorb a whole heap of the vibration and hold the part steady. Of course you have to have a secure mounting method in the jig before you start machining it and you will have to take smaller cuts and what not as the wax obviosly isnt as strong as a large block of metal....

Thats just my idea.

[cjanota]

I would think that lathe followed by wire EDM would do nicely.

[David Goodwin]

Yeh a bloke i know spoke to me about EDM, however im having trouble finding a company locally (South Australia, Australia) who can do it.

Spoke to the workshop again, and we were thinking to machine the one side of the thin section as per Jersey Tom, then use a section of secured foam for the other side to absorb the vibration. That or another form of vibration absorbent material.

I do prefer the idea of EDM tho....ill keep looking.

Cheers, for the help!

[Tim.Wright]

The EDM is a good tool, but it does give a 'slightly' rippled finish and a heat affected zone - neither of which are good for a highly stressed, fatigue loaded part.

Tim

[Chris_S]

Have you looked at wire erosion ?

[David Goodwin]

No, but i was under the impression wire erosion and EDM were the same thing or similar...i may be mistaken tho.

Is there many ways to reduce the rippled finish EDM gives? I have no previous experience with EDM so any advice would be valuable. I was planning on heat treating the parts (all the stressed members in the ARB) after manufacture anyway which should help with any heat affected areas from welding/EDM.

[MalcolmG]

There is an ancient process that is still practiced in small workshops in some villages in mainland Europe known as "filing". The process basically entails the manual abrassive removal of material, using a textured piece of hardened steel; usually shaped into flats, half rounds, or full rounds. I understand that a skilled practictioner of "filing", armed with square or straight edge, is able to obtain an exceptionally flat surface in a reasonably brief period of time.

[Kirby]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MalcolmG:
There is an ancient process that is still practiced in small workshops in some villages in mainland Europe known as "filing". The process basically entails the manual abrassive removal of material, using a textured piece of hardened steel; usually shaped into flats, half rounds, or full rounds. I understand that a skilled practictioner of "filing", armed with square or straight edge, is able to obtain an exceptionally flat surface in a reasonably brief period of time. </div></BLOCKQUOTE>

Wow, get with the times.

Clearly some sort of CNC Filing/Grinding robot is the answer

[jdstuff]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kirby:


Wow, get with the times.

Clearly some sort of CNC Filing/Grinding robot is the answer </div></BLOCKQUOTE>

http://forum.planetisuzoo.com/albums/album22/VR_008PII.jpg

http://fsae.com/groupee_common/emoticons/icon_smile.gif

Seriously though....

Our company machinist is a big fan of using double-sided carpet tape to help fixture thin sections. He's made some amazing parts using this method.

[Benn]

What about waterjet cutting for the arms? Probably a lot easier to find a waterjet place and cheaper then edm.

[Grant Mahler]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Benn:
What about waterjet cutting for the arms? Probably a lot easier to find a waterjet place and cheaper then edm. </div></BLOCKQUOTE>

I don't know about that. 3D waterjetting was quoted out to me at the same price, with worse surface finish, and they had no idea if they could hold the tolerances I was asking. Maybe just my bad luck at the places I talked to, or maybe there is a technology difference. Wire EDM is awesome if you have the time and money.

[Benn]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Grant Mahler:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Benn:
What about waterjet cutting for the arms? Probably a lot easier to find a waterjet place and cheaper then edm. </div></BLOCKQUOTE>

I don't know about that. 3D waterjetting was quoted out to me at the same price, with worse surface finish, and they had no idea if they could hold the tolerances I was asking. Maybe just my bad luck at the places I talked to, or maybe there is a technology difference. Wire EDM is awesome if you have the time and money. </div></BLOCKQUOTE>

Yeah we were thinking of just 2D waterjet cutting the thin areas, then in house cnc'ing the majority of the component. Just using the waterjet to get around the chattering on certain areas. I haven't really had a look at 3D waterjet cutting thou. In the end I redesigning the component so for a very minor weight increase (tiny bit stiffer too) we could in house cnc the whole piece.

[teemee]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by David Goodwin:
I have no previous experience with EDM so any advice would be valuable. I was planning on heat treating the parts (all the stressed members in the ARB) after manufacture anyway which should help with any heat affected areas from welding/EDM. </div></BLOCKQUOTE>

We did our ARB-Blades with wire-cut EDM BUT we did the heat treating as the first step in fabrication.

Worked well, no problems since.

[Brett Neale]

Hey Dave, how's things going back in the UARC shed mate?

Anyways, I'm pretty sure I remember that NTS Tooling in Pooraka do EDM, if not they might be able to help out some other way. Might be worth giving them a call, we have a card of our contact there if you can find it somewhere in the shed.

[Drew Price]

This may be a more simplistic answer than you are looking for, but have you considered buying off the shelf ones, like from HRP? This might be the kind of thing to carefully consider the resources you have, that much setup for anyone but an excellent Uni level machinist will probably take at least a week, and I know we wouldn't have had the time to spare.

Best,
Drew

[David Goodwin]

Yeh things coming along well Brett, chassis is pretty much done, suspension in the workshop being made, and power-train stuff coming along nicely.

Yeh I've found a few tooling places with the ability, however, (most likely) we would require sponsorship to do EDM which has/could be an issue with a few of these tooling type places-especially in the current economic situation.

Drew,
I have designed my current setup around having custom bladed lever arms so changing at this late stage would be quite difficult.

I think best case scenario, we will try EDM. Failing that, I'll let the workshop know of a few of the techniques mentioned above. See how we go! Thanks for all the help!

[Richard Pare]

One method I've used with good results over the years is to turn the taper and ends first in the lathe, and then do the mill work.

Make up a couple of split clamp blocks to grab the 2 ends in 2 vises - the bar is suspended between the 2 vises - OR, if the bar is short enough, make the 2 blocks wide enough to grab in a single vise with enough room to machine the flats.

The flats can be machined in one operation without removing/reorienting the blade to machine the second side. Chatter should be non-existant. If you start getting any chatter, just slow the speed and feed way down for the final passes.

One thing to watch is the size of the radiuses at the ends of the flats compared to the cutter diameter - use a cutter of a smaller radius than the cut radius, and profile the radius. This will get rid of the tendancy of the cutter to overcut the blend from the radius to the flat.

Oh yes : and climb mill, not conventional.

Richard Pare
Indianapolis Competition Products