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chknhwk
chknhwk HalfDork
6/5/19 7:24 a.m.

What is the minimum material you would consider for wheel spacers?  Carbon fiber?  Carbon-kevlar?  ABS?  Aluminum?

stafford1500
stafford1500 Dork
6/5/19 7:31 a.m.

YOu would have to check the material specs for that decision. Primary items I would look for are: plastic transition temp (when it starts to get soft) and Young's modulus (how stiff it is in compression).

 

Basically, think about where it lives and what loads/temps is is likely to see and design above those sorts of limits.

chknhwk
chknhwk HalfDork
6/5/19 7:36 a.m.

In reply to stafford1500 :

So how would I get values of the product in use to be able to compare to plastic transition temp and compression values?  Sounds like a lot of mechanical engineering knowledge I do not yet have command of...

By the way I am in no way condoning short cutting any safety design or consideration, just wondering how one would go about the decision regarding what material to use if one had access to a 3D printer...

stafford1500
stafford1500 Dork
6/5/19 7:42 a.m.

Since you are talking about 3D printing, the plastic transition temperature is below what is required at the print head to actually place the material in a print. If that is lower than the hub temperature after some aggressive braking then you do not want to use it. You could probably get that on-car data with an infrared thermometer. The 3D printing material specs should be available from the supplier.

chknhwk
chknhwk HalfDork
6/5/19 8:02 a.m.

In reply to stafford1500 :

Ah! Or a thermo strip, correct? Granted it is not as accurate but if we're talking outside of 100° allowance we should be good. 

ProDarwin
ProDarwin UltimaDork
6/5/19 8:13 a.m.

Shortcut:  the answer is no, don't do it.

 

They are great for test-fitment though.

bluej
bluej UberDork
6/5/19 8:20 a.m.

I would think that almost any print material that uses heat to place isn't going to work safely for this application. There may be chemical curing options that could work, but I'm not versed in those options. Unless you somehow have access to at-cost printing of the more exotic printers that do do metal, it'll probably be cheaper to machine traditionally.

There may be a path of using a print to create a form for aluminum casting, but I wouldn't use a straight cast w/out machining to make sure the faces are parallel.

Are you changing the bolt pattern? Any reason not to use the cheap "universal" spacers out there?

spacecadet
spacecadet HalfDork
6/5/19 8:29 a.m.
ProDarwin said:

Shortcut:  the answer is no, don't do it.

 

They are great for test-fitment though.

This

 

If you want a custom spacer made. Have it machined. 

chknhwk
chknhwk HalfDork
6/5/19 9:14 a.m.

In reply to bluej :

So the reason for my inquiry was really three-fold:

  • I am looking into some spacers for my specific application
  • I am looking to change the bolt pattern on a set of rotors I have
  • General knowledge attainment

And one again the GRM collective does not fail to deliver.  Thanks!

RacetruckRon
RacetruckRon HalfDork
6/5/19 10:00 a.m.

Going off of what stafford said about the glass transition temp (Tg), the Tg on most polymers that hobbiest grade printers are capable of printing is 80-100°C. 

A lot of easy to print materials won't even hold up well to interior temps on a hot summer day.

bluej
bluej UberDork
6/5/19 10:09 a.m.
chknhwk said:

In reply to bluej :

So the reason for my inquiry was really three-fold:

  • I am looking into some spacers for my specific application
  • I am looking to change the bolt pattern on a set of rotors I have
  • General knowledge attainment

And one again the GRM collective does not fail to deliver.  Thanks!

gotcha.

is there an off the shelf spacer that could have whichever of the patterns is needed be added via machining? might be a way to save some machining cost?

californiamilleghia
californiamilleghia HalfDork
6/5/19 10:17 a.m.

SCARY,  and mostly because it on the wheels , 

But to add a question , could you 3d print a carb adapter that would need to take the temps and vibration of a motor.

 

RacetruckRon
RacetruckRon HalfDork
6/5/19 10:29 a.m.

In reply to californiamilleghia :

A phenolic spacer for a holley 4 barrel is like $18 on Jegs so unless it's some odd ball carb it's probably not worth the hassle.  Is it possible, yeah.

There's a couple facebook groups I'm on where guys are printing their own throttle bodies and velocity stack out of fiber reinforced Nylon filaments. I started playing with that same material for a couple car project of my own, it is wild stuff and makes some really tough parts. It's crazy to think what I can make on a $200 printer and $60 in material.

ChasH
ChasH New Reader
6/5/19 11:09 a.m.

I use flat washers on the wheel studs to emulate spacers and wheel offsets before committing to a final product. If you want an aluminum disc with holes as a spacer, there are many for sale ebay, some of them quite reasonably priced.

stafford1500
stafford1500 Dork
6/5/19 11:31 a.m.
chknhwk said:

In reply to bluej :

So the reason for my inquiry was really three-fold:

  • I am looking into some spacers for my specific application
  • I am looking to change the bolt pattern on a set of rotors I have
  • General knowledge attainment

And one again the GRM collective does not fail to deliver.  Thanks!

If you had said you were looking at wheel ADAPTERs, I would have basically said it won't work. For a basic spacer there is a small chance you could make it work. For adapters, you need to consider the tensile strength and fatigue resistance for the application, not to mention the stress risers of the holes for the studs. Plastic for a cantilevered-cyclic load, with heat and significant shear, is not a good use condition.

Ultimately, wether you have the detailed engineering background or not, you need to think about how something you want to make is going to be loaded/used. If you think about where the loads/stresses go into a part, you can start to decide what WILL NOT work very quickly. Once you think about how a piece is loaded, you can gain some personal insight into strength of materials by trying to duplicate it in a simpler form. Your wheel adapter idea: hold a piece of PVC tube between your hands and bend/twist/heat it and see how much it moves. Then do the same with metal of roughly the same size (aluminum or steel, etc) and note the lack of movement. You do not have to know the exact properties to realize which one is going to move less.

84FSP
84FSP SuperDork
6/5/19 12:19 p.m.

Wheels and surrounding equipment is very close to a no-go in all cases in plastic.  The temp and load cycles would scare me in anything but metal.  I have had issues with spacers I had machined due to balance issues that left me eating three sets of rear wheel bearings before I moved onto off the shelf spacers.

MadScientistMatt
MadScientistMatt PowerDork
6/5/19 1:57 p.m.
californiamilleghia said:

SCARY,  and mostly because it on the wheels , 

But to add a question , could you 3d print a carb adapter that would need to take the temps and vibration of a motor.

 

Instead of 3D printing the spacer, I'd probably use sheet phenolic material and have it water jet cut.

Apexcarver
Apexcarver UltimaDork
6/5/19 2:02 p.m.

To be clear, in order to save a few hundred bucks (tops) from a machine shop (and time/hassle), you are considering making a mission critical component from a material you have not verified the strength of?

 

I have an engineering degree and without conducting an in-depth analysis...  I wouldnt consider making them from anything less than forged aluminum with a machining process. 

 

There may be possibilities with composites, but I wouldnt exactly try it with shade-tree processes and analysis. 

 

theres a few E-machine shops around where you can send a design file and get mailed your part. Thats what you are looking for. 

ProDarwin
ProDarwin UltimaDork
6/5/19 2:37 p.m.
Apexcarver said:

To be clear, in order to save a few hundred bucks (tops) from a machine shop (and time/hassle), you are considering making a mission critical component from a material you have not verified the strength of?

This comes off as a bit harsh. What he was asking is what materials could he consider making something out of.  The answer was a resounding "not plastic".  Question answered. 

californiamilleghia
californiamilleghia HalfDork
6/5/19 2:48 p.m.

Is this  only a trial fit for clearance ?

If so you could use steel washers as said above , or even layers of plywood etc.

I would think you would want too mock it up for clearance before paying for  finished parts

stuart in mn
stuart in mn MegaDork
6/5/19 2:54 p.m.

I've seen plastic used for hubcentric centering rings, but not spacers.

Apexcarver
Apexcarver UltimaDork
6/6/19 1:28 p.m.
ProDarwin said:
Apexcarver said:

To be clear, in order to save a few hundred bucks (tops) from a machine shop (and time/hassle), you are considering making a mission critical component from a material you have not verified the strength of?

This comes off as a bit harsh. What he was asking is what materials could he consider making something out of.  The answer was a resounding "not plastic".  Question answered. 

Yeah, sorry...  side effect of working in a safety office.

DrBoost
DrBoost MegaDork
6/6/19 3:14 p.m.

If you are looking to make custom pieces and want plastic ones printed for mock-up, let me know. 

chknhwk
chknhwk HalfDork
6/6/19 7:24 p.m.

Great info everybody, thanks again!

I agree, the answer is a resounding no for any plastic. I didn't think I could anyway but I always like to know WHY. 

My uses are wheel spacers (I'll just order some online) and TEMPLATES allowing me to redrill brake rotors, going from a 5x4.5" bolt pattern to a 5x4.25" reliably and accurately. NOT adapters. This is just a thought process that I thought I'd share with the collective. 

Thanks again! I appreciate ALL the input.

californiamilleghia
californiamilleghia HalfDork
6/6/19 7:45 p.m.

CNC bolt circle is an Android app that might help you mark things out.

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