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Lightweighting and aerodynamic optimization of a subcompact car.

neptronix said:
Something i never thought about is the weight of the lead acid battery. Mine's the size of something that would be in a V8/V6 car and weighs 35lbs. I have no clue as to why this car has such a large battery. Perhaps an oversized parasitic drain.

Braille makes low internal resistance AGM batteries for cars between 6 to 21lbs. The 15lbs one seems very reasonable and is recommended for use in cars larger than mine. Mine is oversized so i should keep it somewhat oversized.

Seems to me that you could use a much lighter pack of A123 cells to get the same effect.
 
Chalo said:
Seems to me that you could use a much lighter pack of A123 cells to get the same effect.

I wish! The big problem with lifepo4 as a car battery is that most alternators want to charge a little higher than the HVC of the cell. If you adjust the alternator's charging voltage downwards ~0.2v to compensate, things like the direct injectors might perform less efficiently, etc..

LTO's voltage curves would be an excellent match, but because the alternator would float it at 50%, the inherent balancing properties of the cell never get activated.. therefore you need a BMS, which is an annoying failure point to add to your car. Retail price on a decent one is around $1000 too, for a mighty 120-150 watt hours :roll:

The braille battery at around $200 is the most economical and reliable choice here.
 
I just signed the papers on a ~300 square foot warehouse space which has adequate room for a machine shop on one side, car or crapton of bikes parked in the middle, and electronics shop on the other side.

Looking to invest in a small CNC machine, tig welder, and other things i've dreamed of for many years.. pretty exciting.

More to come!
 
CONGRATULATIONS!

You can't do much without a shop. I remember when I got my first crappy dirt floor single car garage. I was in hog heaven for days.

Did you luck out and get 220V? No matter, you can get by on 110V just fine.

Start checking Craigs's list daily for used tools. You'll need a bench w/vise first thing. Too bad you're not still in SLO. I could have set you up with a bunch of tools. Buy used and don't pay more than ½ the price of new or less if the tool doesn't look almost new.

Get the basics first. Must have is a bench top drill press and 6" grinder. It's ok to buy Harbour Freight at first. If you find that you use the tool and it craps out, then buy a better one. The tools I rely on are 1st class professional ones, but you be surprised at how many cheap HF ones I still use. With the exception of my MiniMax bandsaw and sliding table saw it seems that most of my lg. stationary tools ended up being Grizzly. Don't end up being a tool snob. Tools are for using, not just polished up sitting on a shelf.

Don't forget tooling. Over the years you'll find that you will spend more on the tooling than the tool itself.

Have fun and enjoy the journey! Nothing better than making stuff! 🛠🔩⚙🗜🧲📏📐🚲🏎

Just don't put your eye out... :mrgreen:
 
Yeah i have a shit ton to learn and a shit ton to buy.
I'm a fan of thrift stores and garage sales so a lot of the basics will be bought there if possible.
Not sure if i have 220v access in my corner; plan to buy everything to work on 110v if possible.

Thanks for your encouragement.


I'm still not moved into the shop fully but i do have one thing to report.

My ~month long mpg is 51.5mpg, up from 45.6mpg when i started.
I still haven't hit 70mpg for a trip but upper 60's happen more often than not.
This is impressive considering i've been using the AC and shuffling around 50-100lbs of stuff frequently lately, and doing less highway driving. I think these modifications have made a big impact.

I test drove a new miata and inspected it's structure. Lots of missed opportunities for efficiency.. barely squeaked 41mpg out of it while hypermiling. Shame that their smaller car isn't *more* efficient.
 
Get the basics first. Must have is a bench top drill press and 6" grinder.......
.... yes, but get the BENCH first ! .... ( workshops most used piece of kit !)
Lots of clean worktop space, and make it plenty strong with a good 4”+ vice bolted to it on one corner ( left or right handed ?)...
And try to keep organised with tool locations and storage as you go, otherwise you will be like me , spending more time figuring out where you last put that tool,.....than actually using it ! :lol:
 
Hey all.
It's summer here and of course the MPGs are dropping like a stone. I get mid 50's on a good day now..

The air conditioner on the car is weak and runs at a 100% duty cycle and cannot keep up with the ~100F temperatures outside.
Typical for a subcompact..
I now realize i made a big mistake in buying this car - dark exterior and dark interior is bad news. I also live at 4500ft elevation, so the sun is extra intense. So that doesn't help.

I've found out that 3M makes some nano ceramic tint that's nearly transparent but can reject >60% of the incoming UV/light, and the resulting heat. That should lower the duty cycle of my AC and increase my car's efficiency notably during the summer. meaning to get that tint done, and also fill the backseat with a very large box to reduce the cubic square ft the AC has to cool.


It's also way too hot to do anything in the workshop so all manual labor is on hold.

I desperately want to make a prototype of my air filter and have lots of car aerodynamic aids to experiment with, so i've been looking into tools.

Since the car and the air filter housings will require me to cut through a lot of plastic, thin metal, etc, i figured i could do this with my Dremel 4300 and a dremel branded diamond 1 1/2 cutting wheel.
Well i overheated the motor and blew it very quickly.

So i went looking for something more powerful than a dremel.. and.. WOW that is VERY hard to find!
You either get an overpowered industrial tool akin to a small angle grinder with no speed control that's too heavy in the hand for good precision..
Wimpy Chinese garbage for under $100..
..or you fork out for a $500 foredom brand flex shaft grinder setup which is only rated for 1/3rd of a HP and uses a huge and brutally inefficient brushed motor.

..yet i can buy a 13000w angle grinder for $50.
Seriously, what gives on these pricing models?!


I can't help but think a hobbyking RC motor and cheapo brushless controller would make an ideal 1/2 horsepower rotary tool for my use. Buy another and use it as a lightweight table saw too.

..but now i need a lathe to make the shaft adapters.. :lol:

So.. how do i get into a small sized lathe that isn't a piece of crap?
 
neptronix said:
Hey all.
It's summer here and of course the MPGs are dropping like a stone. I get mid 50's on a good day now..

A/C or gasohol? Or something else yet?


...or you fork out for a $500 foredom brand flex shaft grinder setup which is only rated for 1/3rd of a HP and uses a huge and brutally inefficient brushed motor.

And they run really slow compared to a Dremel. But they don't overheat!

I can't help but think a hobbyking RC motor and cheapo brushless controller would make an ideal 1/2 horsepower rotary tool for my use.

I imagine the gyro precession on a handheld tool like that would be detrimental to precise operation.

So.. how do i get into a small sized lathe that isn't a piece of crap?

Sherline has been the reputable name in tiny lathes for many decades. Taig is also good. Both are USA made, last I checked.
 
Chalo said:
A/C or gasohol? Or something else yet?

Haha, we're not that far yet..

...or you fork out for a $500 foredom brand flex shaft grinder setup which is only rated for 1/3rd of a HP and uses a huge and brutally inefficient brushed motor.

And they run really slow compared to a Dremel. But they don't overheat!

Yes, the foredom TX 1/3rd HP rated model only spins at 15,000rpm.. but.. does the additional torque from such a large motor make up for it, vs a dremel where you have high RPM coming out of a motor that will stall if you look at it wrong? :)

I can't help but think a hobbyking RC motor and cheapo brushless controller would make an ideal 1/2 horsepower rotary tool for my use.

I imagine the gyro precession on a handheld tool like that would be detrimental to precise operation.

Yeah i'd have to go with a flex shaft and mount the RC motor to the table etc.
Otherwise i end up with a two handed tool like this 1700w beast from dewalt:
download (6).jpg

So.. how do i get into a small sized lathe that isn't a piece of crap?

Sherline has been the reputable name in tiny lathes for many decades. Taig is also good. Both are USA made, last I checked.

Hey thanks for the tip!

$655 for a small lathe isn't too bad:
https://www.sherline.com/product/45004530-lathe/

taigs are cheap but don't come with all the accessories..

I can see myself making:
Bicycle parts ( maybe as large as a mid drive reduction unit )
Shaft adapters galore for my air filter motor to blade connectors.
A few chuck adapters for my hobbyking motor based rotary tools.
.. and maybe in the future..
A ~4 inch diameter pulley for adding a very mild 1kw hybrid system to my yaris.

Can i get durability and precision in a smaller lathe for under $1000 for these sorts of things?
 
neptronix said:
Yes, the foredom TX 1/3rd HP rated model only spins at 15,000rpm.. but.. does the additional torque from such a large motor make up for it, vs a dremel where you have high RPM coming out of a motor that will stall if you look at it wrong? :)

15k RPM is much faster than the Foredom tools I remember using in college.

Yeah i'd have to go with a flex shaft and mount the RC motor to the table etc.
Otherwise i end up with a two handed tool like this 1700w beast from dewalt

For me, the next step up from a Dremel is a pneumatic die grinder. If you have an air compressor, I'd consider that (even if it means adding a supplemental reservoir tank).

I can see myself making:
Bicycle parts ( maybe as large as a mid drive reduction unit )
Shaft adapters galore for my air filter motor to blade connectors.
A few chuck adapters for my hobbyking motor based rotary tools.
.. and maybe in the future..
A ~4 inch diameter pulley for adding a very mild 1kw hybrid system to my yaris.

Can i get durability and precision in a smaller lathe for under $1000 for these sorts of things?

For making things over about 2" in diameter, a wee lathe like Sherline is out of its league. It's not so much a matter of durability or precision, but how big a bite you're able to take with a tiny lathe, and the physical limitations of the diameter and toolpost range of movement.

Check out This Old Tony's YouTube videos on working with, and upgrading, small imported lathes.
[youtube]05vUCdzhoe4[/youtube]
 
Chalo said:
15k RPM is much faster than the Foredom tools I remember using in college.

Yeah 15krpm doesn't seem too slow. I can go through half inch steel at a pretty decent rate even with the dremel 4300 at that speed... until the motor burns up :shock:

Chalo said:
For me, the next step up from a Dremel is a pneumatic die grinder. If you have an air compressor, I'd consider that (even if it means adding a supplemental reservoir tank).

Yes i actually did consider setting up a 100% air tool shop.. it makes a lot of financial sense..
The only problem i have is the power from the wall is weakish.. i'm told i need a 10 gal tank at a bare minimum and units which have tank sizes that big want to draw the full 13-15A from the wall. That's a fire waiting to happen with my electrical system at the workshop :/

Could i use an 8gal unit with less instant power ( 1hp? ) and hook another 8gal tank to it and effectively have 16gal - enough power, but with a low duty cycle? Would this effectively just be like having an ebike with a small battery but super big capacitor to deliver the needed power in bursts?

Chalo said:
For making things over about 2" in diameter, a wee lathe like Sherline is out of its league. It's not so much a matter of durability or precision, but how big a bite you're able to take with a tiny lathe, and the physical limitations of the diameter and toolpost range of movement.

Check out This Old Tony's YouTube videos on working with, and upgrading, small imported lathes.
[youtube]05vUCdzhoe4[/youtube]

That was a super excellent video on the reality of making a smaller lathe work :thumb:
So i'm probably looking at a 14-17 inch lathe at around a $1000 entry point, huh?

The cheap imported ones sound like more of a headache than i'd like, as a newbie.
 
I think Dremel tools are overpriced for the quality you get. I've been buying Black & Decker ones. They seem to last longer and are cheaper too. I found some replacement chucks on AliExpress to get rid of the crap 1/8" and 3/32"" collets that come with these type of tools.
2021-06-18 12_57_06-Photo - Google Photos.png

I had a used Foredom but sold it as I found it not too useful for what I had to pay for the thing.

Lathes are a lot of fun, but beware of the tooling rabbit hole. I spent twice what I spent on the lathe for the tooling necessary to do any real work. If you do buy one, buy it used. There are a lot of hobby guys that give up and sell their almost new lathes for cheap. Like Chalo mentioned, "This old Tony" is a good Youtube source.

I'd keep an eye out for an old belt driven air compressor. The direct drive ones will drive you insane with the excessive noise.

If I didn't have a good fan in the shop, I wouldn't spend much time there in the hot months.
 
neptronix said:
Could i use an 8gal unit with less instant power ( 1hp? ) and hook another 8gal tank to it and effectively have 16gal - enough power, but with a low duty cycle?

That works pretty well, in my limited experience of having supplemental air volume. The more reserve air you have, the longer you get to work before it's depleted. But then it takes longer to pump back up. For some applications, that's a fine compromise, but for others it can be a deal breaker.
 
I'm so glad i can come on this forum and get machine shop knowledge too.
I haven't stopped learning things here since i joined in 2010 :es: :thumb:

Thanks Nicobie and Chalo for your help!

How picky do i need to be about compressors?
This one is appealing due to it's low noise and high efficiency:
https://www.californiaairtools.com/...actor-grade/1-0-hp-air-compressors/cat-8010a/

I could go with a used one too, yeah.

Yes i think Dremels are also super overpriced.
How can i buy a harbor freight Dremel 4300 power equivalent for 1/4 the price?
How can i buy a DeWalt die grinder for 20 bucks more which has 3 times the power?
It doesn't add up!

I was thinking of the fore unit because it takes a 1/4 shaft which means i could in theory hook something up as large as a 3 inch cutting wheel.
But if i have air compressor power then it's just stupid to pay that much for an electric tool with a basic brushed motor in it.

I must admit that i didn't do my homework before buying the dremel. I figured i was putting good money into their biggest model and would get good product out. I mean i have a 10 year old dremel here that's still kicking.. but.. yeah. Now i know.

I'll consider buying a lathe used. The only thing is that i have no idea on how to assess the value of one. Is it the case that you can just fix/replace every part and don't have to worry much about running into proprietary part availability?
 
neptronix said:
How picky do i need to be about compressors?
This one is appealing due to it's low noise and high efficiency:
https://www.californiaairtools.com/...actor-grade/1-0-hp-air-compressors/cat-8010a/

That's the only brand of air compressor I've used since I first tried one a few years ago. The bike shop transformed from a place where all conversation had to pause when the compressor topped up, to a place where you hardly notice it's working. I can't recommend them enough.

The pedicab shop got two of them; one for general shop use and tire inflation, and a small one to run a pop riveter.

The Atlas 10 inch lathe is in my opinion the gold standard of home machinist bench top lathes. But it's not small enough to tuck away between uses, and it's popular enough to hold its value well. If you have a space you can dedicate to it, you won't go wrong to try one. You can always get your money back when you sell it on.
 
Wow ok.

I figured 'decibels per horsepower generated' might be a metric of efficiency and thus maybe longevity as well, which is the main thing that attracted me to the California air tools unit. I don't see any sound dampening features on the unit so that's not the reason.

All i know about air compressors is what i gleaned from a 30 min conversation with the division manager of harbor freight who just happened to be in the store that day. :lol:

Those compressors are awfully cheap too.
 
I agree with Chalo. If I was to buy a new small compressor I'd buy the CAT one. The old Atlas lathes are also excellent.

Lathes don't so much break as they just get less precise. IMHO even a worn out one would be good enough for what you will be doing.

Look for used stuff. Just be sure to try it before buying. You'll be needing to check Craigslist and Facebook Marketplace a couple times a day, but you'll find what you need sooner or later. Try to be patient. :wink:

This is the last lathe we got for <$1k from The local Space Force Base (Vandenberg). It had never been used and was stored outside for at least a year. :cry: But it cleaned up nice. Was hell to move!

2021-06-18 15_25_22-Photo in ken's shop - Google Photos.png
 
nicobie said:
I agree with Chalo. If I was to buy a new small compressor I'd buy the CAT one. The old Atlas lathes are also excellent.

Lathes don't so much break as they just get less precise. IMHO even a worn out one would be good enough for what you will be doing.

What does that 'less precise' look like? producing parts with play in them, or just moreso play in adjusting the lathe/positioning the piece/etc?

The one mission critical thing for a lathe to do for me is create shaft adapters for my air filters. I believe the motors will be spinning at least in the hundreds of RPMs, and i want the shaft adapters or shaft machining ( whichever way i plan to go ) to be *perfect*, as there's i think no room for error there.

nicobie said:
Look for used stuff. Just be sure to try it before buying. You'll be needing to check Craigslist and Facebook Marketplace a couple times a day, but you'll find what you need sooner or later. Try to be patient. :wink:

I wouldn't know how to test out a used air compressor or lathe tbh, so that's a problem :pancake:

Also, that lathe is freaking nuts. What have you managed to make with it?
 
By worn out I mean instead of tolerances of .00005", you'll only get .0005". plenty good for a fan mounting collar. You'll have more problems drilling the fan mounting holes for the collar.

Easy to check compressors. All they need to do is start and turn off at the proper psi and pump and hold air for at least ½ an hour.

That big lathe was mostly used for shortening drive shafts and narrowing race car differentials.
 
Back to your first issue of cutting lots of thin metal , plastics etc..
Dremmels are hobby tools, toys really compared to workshop equipment.
Air tools are the professional solution, but you are “tied” to the shop or length of airline for use.
For cutting metal (sheet or anything up to 2” tube) , its hard to ignor the 4” cutting disc in a small angle grinder ($20-$50 for home use) mains power is cheapest and simplest.
A decent cordless angle grinder is tempting but dont underestimate the power/torque needed to cut through metal
If you go with anything battery powered, pick a make that has a good range of shop tools using the same battery packs
Check what the trade guys are using ? deWalt, Millwalkee, Makita, ? Etc
A lathe is only useful if you have the experience to use it. They are probably one of the worst ROI investments in a shop, invaluable for certain jobs, but unused 95% of the time, unless you are contract machining multiple pieces.
Remember, there are multiple small machine shops in every town who will turn up a few parts at prices much more economical than your own lathe + time
 
Hillhater said:
Remember, there are multiple small machine shops in every town who will turn up a few parts at prices much more economical than your own lathe + time

That's a very good point and instead of investing in $1000, perhaps early production of things can be outsourced at first then moved in-house later.
I guess i just hate waiting on people and like to do 100% of everything myself, but you are right, that is a lot more sane.

I do have an angle grinder currently but the on/off switch and bulkiness makes it very hard to be precise with it. It's also loud AF. I think it is the largest type you can get.


On another note, i did look at the black and decker RTX a bit more.
It is rated 2 amps at 120v so it's stronger than the biggest dremel. That's good.

I see that black and decker sells a pretty decent flex shaft for the RTX too.
Perhaps it would be reasonable to make one stationary mounted, use a flex shaft, remove the inner fan, and add an external forced air system so i can gain back a few watts of rotating power.

The 10x more expensive foredom is rated at 1/3hp which works out to 240w.
The RTX is 2 amp x 120v = 240w.

Nicobie, i think you just saved my newb ass a lot of money :lol:

Maybe this would work.. i could produce all the weird curvatures on the ABS/Acrylic yaris aero panels and also do the fine machining for the air filters ( countersunk bolt grooves, air slots, that sort of thing ) as well using the 'BD' :wink:

Could probably mount the current very loud angle grinder to a plank of wood and turn it into a bench saw with guides so that i can kick out air filter panels and aero panels with ease.

( what i need is a super huge cutting area but very little power, so buying a large table saw new seems unreasonable )


If air filter production gets serious, then air tools seems like a good route simply because they are so cheap and durable once you invest in the compressor.
 
Yes. A good plan. Like that irritating commercial goes, "Only buy what you need."

Turn that cheap angle grinder into a stationary tool

https://www.walmart.com/ip/Angle-Grinder-Cutting-Bracket-Angle-Grinder-Special-Cutting-Machine-Accessories/244669909

The best and most useful tool you'll ever own is the one between your ears. :mrgreen:
 
neptronix said:
Hillhater said:
Remember, there are multiple small machine shops in every town who will turn up a few parts at prices much more economical than your own lathe + time

That's a very good point and instead of investing in $1000, perhaps early production of things can be outsourced at first then moved in-house later.
I guess i just hate waiting on people and like to do 100% of everything myself, but you are right, that is a lot more sane.

Well, yes.

Here's the one that just came to stay at my house:

IMG_20210618_201942966.jpg
 
nicobie said:
Yes. A good plan. Like that irritating commercial goes, "Only buy what you need."
Turn that cheap angle grinder into a stationary tool
https://www.walmart.com/ip/Angle-Grinder-Cutting-Bracket-Angle-Grinder-Special-Cutting-Machine-Accessories/244669909

You know i've seen things like that and question how sturdy they are.
But this one is interesting because it mounts to the grinder's guard. Pair that with the handle mount bolt hole and those two mounting points should be pretty stiff.

Thanks for that, i think i should throw that on my order list.

nicobie said:
The best and most useful tool you'll ever own is the one between your ears. :mrgreen:

The second best tool is using others' brains when yours is lacking :es:

You guys helped me a lot here and i gotta say thanks again.

I ordered two black and decker RTX's, a foredom foot pedal, a 12w blower fan, and a flex shaft as well.
I'd like to experiment with hot rodding the black and decker further too, and if successful, will detail the mods :mrgreen:
 
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