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TOTW: Advanced fabrication

10K views 28 replies 17 participants last post by  ccj8008 
#1 ·
Welcome to the next installment of the

Topic of the Week

We covered Basic shadetree fabrication a while back.

This week, most of us are probably just going to sit back and listen to what a few can talk intelligently about: advanced fabrication.

Many of us have welded angle or tube together to make some crude device - a cross member, a motor mount, or a skid plate.

But let's talk about some of the more advanced stuff: mills, lathes and the like.

So, who's going to start?
 
#4 ·
Travis Waldher said:
Well... I've seen a mill and lathe in action. (The mill was coolest)

But... that doesn't count. :flipoff2:
Well, I've actually run both a mill and a lathe - but I was making parts out of lexan/plexiglass type stuff. Not sure that qualifies. If you mess up, you don't break anything...
 
#7 ·
a Tap/Drill chart is your friend. get one (usually free) and use it.

basic machining (mills and lathes) just take some practice to get used to. you really have to develop a feel for what you are doing. it also helps to have somebody around that knows how to do what you want to do.

DATUM: a known point of reference where you base all of your measurements.

example: lets say you need a hole every 12" down the length of a piece of angle iron. instead of measuring 12" to the first hole, then 12" from that hole to the next, then...you make a mark at the 12" point, then 24" point, then 36"...etc. if you don't you'll get some accumulated error which could put the last hole quite a ways off. this goes for machining too. always reference the same point when possible.


its easier to answer questions on these topics than post information...so ask away!


drill bits and taps: don't bother with the Titanium BS. get good, american, high-speed steel (HSS not HS) and they will be fine. sometimes you'll need Cobalt for the tough stuff.

find a local industrial supply that deals with "joe public" and has good prices. some that come to mind are: Wholesale Tool (www.wttool.com), MSC, JL Industrial.

buy steel from the steel houses and now the local hardware. ask what the price breaks are. sometimes, when you buy more steel, you pay less. EX: lets say less than 100lbs of steel costs $1.00 per lb and over 100lbs cost $0.80 per lb. so, 90lbs of steel would cost $90 and 100lbs of steel would cost $80. steel guys are tricky like this.
 
#8 ·
Yeah.. steel guys are tricky like that.... last I looked at buying steel.

0-whatever was around 75 cents a lb.

4,000lbs was at 25 cents a lb. (e.g. enough to build a big trailer)

K... question..

When fabricating an adapter for a rear axle housing that will have a press fit in to where the bearing race is, a press fit recess on the outside of it for a spindle, 4 bolt holes for bolting to the flange, and obviously hollow in the center to accept up to a 40 spline axle.

What material should you be using? Is standard Mild Steel enough or does it NEED to be more exotic? Would it be better if it was a more exotic metal, if so which type?
 
#9 ·
Keith Strong said:
Maybe we should get examples of specific types of advanced fab.....What qualifies as advanced vs. beginning?

:beer:
I'm thinking "requires tools beyond a welder, angle grinder, and chop saw"

If it's in MOST of our garages, it doesn't qualify.

Things most of us would farm out, but would like to know more about.
 
#12 ·
vnc and cnc machines can be used to make anything you can think of if you have the right tooling avaliable , in fact you can go so far as to build your own engine if you feel like taking the time to set the machine up for the various passages and other various holes.
 
#13 ·
jeepnmatt said:
example: lets say you need a hole every 12" down the length of a piece of angle iron. instead of measuring 12" to the first hole, then 12" from that hole to the next, then...you make a mark at the 12" point, then 24" point, then 36"...etc. if you don't you'll get some accumulated error which could put the last hole quite a ways off. this goes for machining too. always reference the same point when possible.

find a local industrial supply that deals with "joe public" and has good prices. some that come to mind are: Wholesale Tool (www.wttool.com), MSC, JL Industrial.
... also known as Baseline Dimensioning versus Chain Dimensioning.

Fastenal is another excellent source for tools, tooling, and ... fasteners. Despite the fact that they primarily deal with high volume contractors and manufacturers, if you go in there with their part numbers and quantities written down, they are pretty cool even with the "onesy, twosy" orders.

cmk
 
#15 ·
It's Milling time

I went and bought a smitty Combo MIll,lathe,drill press set up for my home fab stuff and it beats the hell out of grinding and cutting
This thing may not be a cnc machine but it has made a lot of great stuff. Im just getting into the more complex things. I have built a few dies to bend tubing 3/8-11/8. worked great to make roof racks and rubicon racks. The hardest part is the milling Surface milling and getting the part set and tied down secure to minize movement. some of this stuff is a sience or art.
 
#17 ·
Boy where to start? I totally agree with JeepnMatt about getting a tap/drill chart. without that you are just guessing most of the time as to what size drill to use and for me it is all about using the right tool for the job. I know some that can build great things with just a torch and a file but thats not me. For me the reason I know what I know is because I am not affraid to tear into it and possibly fuk it up. So through the diversity of projects comes knowledge.
Here are a few tools or tricks I use.
1) I almost never use a tap handle to do any tapping. I use a variable speed cordless drill or do my tapping on the lathe or the mill. Most tapps break because they get side loaded or because you used the wrong drill(back to the tap/drill chart)
2) When welding box tubing I use magnets to hold the part in place for the first tac-weld then I check square from corner to corner and then tac-weld it to the table to hold it in place so it doesn't move or twist.
3) If you are going to making more than one of something that take the time to make a jig, stop, or fixture so that each part turns out the same.
 
#18 ·
Dean, i agree with you on learning how to do things myself...i call it "education".

yeah, i could pay some numb-nut $60 an hour to rebuild my transmission...or, i can buy myself some cool tools, a couple service manuals, and take a few hours to do it myself. more times than not, it comes out fine. if i fuk it up, i consider it a learning experience and fix it.



hey all: i work part time at a machine shop that almost went bankrupt. there are A LOT of shops going under right now and now is an excellent time to pick up used machine tools. the only problem is most are 3-phase powered, which would require you to buy a rotarty phase converter. even the most worn out machine tools should be fine for home use. they just aren't much good for running productions jobs. you might want to call around to some used machinery dealers and tell them your story. go check the stuff out ant let them know you are looking a couple other places as well. this will motivate them to get there prices down so you pick them...
 
#19 ·
jeepnmatt said:
hey all: i work part time at a machine shop that almost went bankrupt. there are A LOT of shops going under right now and now is an excellent time to pick up used machine tools.
Unfortunately, that has been the story around the chicago-land area for the past 3 years. There is a TON of used capital out there for sale, cheap.

cm "educated ... many a time" k
 
#20 ·
Milling about

I got the smitty mill,lathe,drill press for around $2k but the bits,cutting tools, holding fixtures calipers gages and measuring devices are the main cost when doing this stuff. Let me tell ya my wife would come out to the garage and say is 10:00 time to stop & Ok Ok 5 min more next thing you know it's 1:00AM.

But having one of these things is like a drug I've made greaseable shackles, bushings. threaded rod ends and lots of neat shit. The guys at the local metal supply know me by name.
 
#21 ·
For a cheap starter drill/mill consider the one in harbor freight for about $375. I know that this isn't the best machine; I have a mill and a lathe that are great but are not in my garage (no room), but this one is great at small jobs and is perfect to get your feet wet. I may get hacked for sugesting this but when you start working with this stuff you are going to screw something up. Better something cheap to start with. Just my .02 and no I do not have an interest in Harbor Freight
 
#22 ·
I've used the Smithy and many other mills/lathes, and I'd say get a seperate mill and lathe if you've got the room.

This way you'll be able to machine much larger parts on both machines and you'll also have the added horsepower each single machine provides, greater adjustability too.

South Bend lathes and Bridgeport vertical mills are everywhere and can be had for as little as 500 ea. Have somebody adjust the backlash in the lead screws for you and your good to go.
 
#23 ·
I just started a Tooling and Machining Technology program at my community college and I love it. My dad has been a toolmaker for over 25 years, and he just now, in the last 5 years built a shop and purchased a used Bridgeport vertical mill, a horizontal mill, and a 13 inch (swing) Southbend lathe. He buys his from auctions, like they said, companies going under. He bought his lathe from an auction for a trade school. He also lives on ebay for tools. Being experienced, he knows what to look for. He did get them pretty cheap though. And his old used Bridgeport has a LOT less slop in the screws than the newer Klausings at school. I'm learning how to make a lot of cool stuff, but haven't made anything much for my jeeps. I did mill an angle on my bracket for my front track bar. But I got a '81 CJ-7 sittin in the barn with the frame off that I'm sure will require some mill/lathe work. Anyways, from what my stupid newbie ass has seen, watch for tool auctions and check out ebay.
 
#24 ·
Where do you go to school in OHIO?

I'm going to Northwestern Ohio in January for Automotive Performance.

I am transferring from Purdue, where I studied Computer Technology, and Electrical Engineering Technology, and women, beer,women,beer,women... you get it..

Finally gonna do something I like.
 
#25 ·
I go to Sinclair Community College in Dayton, Ohio. I was going to the University of Cincinnati last year, trying to get in their Mechanical Engineering Program. But damn, transfering in their was gonna be a real bitch. I would have to have a ton of classes just to get in their 5 year program. Plus I took a heavy load of beer and bars as well. Sinclair is great for a community college, cheap. I just want to get a good job doing things I like, I've already got my Aviation Maintenance Airframe and Powerplant licenses ( during high school ), and I would like to do that, but everyone keeps saying "get your degree". I'm doing this machining program mostly because of everything I've read on here.
I originally registered here in February when I was at UC. I would just sit on my DSL and research all day, instead of going to half of my classes. I didn't post so long, partly because I searched and found everything, partly because I didn't know shit.
Anyways, I would love to take something like Auto Performance. That would be awesome.
 
#26 ·
I'd say the reason you're Bridgeport has better backlash than the Klausing is maintenance. Our Klausings are kick ass, I prefer them over the Bridgeport and Seiki. Seiki's are cheap but nice. I got to use an Okuma Machining center for the last couple of months, man was that nice. You can find the $500 Bridgeport, but it's more typical to be in the $10-1500 range. Endmills, Drill bits, carbide inserts, and tooling of that sort can be had fairly cheap in weight allotments on ebay. Drill chucks, collets, and a good vice you shouldn't really go too cheap on.

One thing to remember about machining for press fit. If you're taking off a lot of material, leave some extra material on it. When it cools down you may have lost your press fit.

Easy
 
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