Bent Fab CH2

[jeepinmatt]

So today Steve and I got a lot done, but don’t have much to show for it. Haha.
First we started with cleaning up.
Cleaned his 6.0 up with degreaser and pressure washer. Then we drug one of my dads th350 out and pulled the converter and drained all the oil out. Next we cleaned up Steve’s atlas.
Once everything was cleaned up, we got the chassis back up in the air and got the frame table back under it, to hold the belly at 20”.

I think the belly will eventually end up around 18” but I built the frame stand/table to be 20” to build from.

After cleaning and reorganizing and putting stuff away where it belongs, and just less clutter of parts strewn everywhere, we slid the trans and case into the belly.

this required us bolting the bent fab th350/atlas billet adapter onto the back of the 350.

next was shoe horning the 6.0 into the front of the chassis, and up onto the legs of the front of the frame table/stand.
Everything we read , says the engine has to come out the bottom, so we installed it that way.

at this point we wanted to bolt the drivetrain together and start looking at mounting it all.

I was wrong. There it is, I admit it, it’s happened before, it’ll happen again.

in my quick thinking and bench racing over the last couple weeks, I said:
“No need to change the atlas input from 32 spline to 27 spline yet, 32 is greater than 27, the atlas input should just slide over the 27 spline 350 output no issue. As long as we have the correct adapter, we can mock it up!!”
I was completely wrong!!!! It won’t go in, no matter how much wiggling and aligning you do.

next, the 350 we were using for mock up has an extra deep pan, that won’t work either. Raises the trans up too much and puts the case at a weird angle to the belly and bottom of the seat tubes.

So no more mocking up drivetrain until we get the atlas input swapped, and the a standard pan on the 350.

good news is, the 6.0 will come out of the top of the engine area, it’s tight but it fits out the top. This is without the front X tubes (35,36,37) in place.

looks like we will fab a removable front X brace so the motor can come out the top.

it was bugging me that everytime you want to pull the engine, you have to pull the front axle out.

Probably isn’t a big deal in all reality, unless changing the trans or converter would mean pulling the engine, and in turn pulling the front axle. That would be a large snowball.

at this point we started looking at link mounts and all from bent fab.
Steve purchased the modular rear link kit, which has wayyyy better geometry than the basic kit, and is the same mounts Tim @ Bent fab uses for his trailing arms.

so at that point progress on drivetrain mounting was halted, we thought we would bolt these assemblies together and tack them up ready for install.

this is when we discovered, that all Tim’s plasma cut holes are all under size. Looking at the holes, he hit several with some type of wheel, as 1/4 to 1/2 the plasma cut edge shows signs of drilling/cutting etc. However a 3/4” bolt will not fit through the holes.

This is 56 or so holes through all the tabs, brackets, and reinforcing plates need to be drilled out to 3/4 to allow the bolts to pass thru.

so we checked some more 3/8 plasma holes for the motor mount package, and half the holes are drilled for the correct size (10mm for head mounting) yet the 3/8 plasma holes barely allow a 5/16 bolt to pass thru.

drilling a plasma cut hole is terrible. The plasma cutting operation leaves an oxide layer that is also hardened due to the extreme heat (45000-55000°F). This will kill a high speed steel or TiN coated HSS bit in seconds. The oxide and plasma hardened area is harder that the HSS.

Now when I cut holes on my crossfire pro table, I cut a test hole in scrap, check for bolt pass thru, and adjust my hole sizing before I cut the final part. OR I cut a .250” hole for location knowing I have to drill out larger. Typically I then use a stone wheel in a die grinder to remove just tiny amount of this hardened area and then hit with normal HSS or step bits.

Another option is to use a drill that is harder than the oxide and heat hardened area. Carbide.
So Steve went a grabbed a 3/4” masonry carbide tipped drill, chucked it up in the drill press and started drilling. I touched up the carbide to bring the OD down a little, and to increase the rake on the carbide cutting edge. It works, and makes a nice hole, but takes a lot of cutting pressure.
Going to take a while to do all 56ish remaining holes.
It’s also such a pain bc the holes are currently about the same size as the minor diameter of the 3/4” thread on the bolts. So it’s not like we have to remove a lot of material, but it’s all that oxide and hardened area.
It would be easier to take the hole from 1/8 or 1/4 up to 3/4, than what we need to do.
Steve is maybe calling Tim in the morning when cools off some haha.

I didn’t take many pictures today as I was tired and sore, and was focused on what we needed to accomplish. I’ll try to not let it happen again.

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we also discovered that the poly bushings as part of the kits to mount the motor and tcase use a 1/2” bolt but have tabs with 5/8” holes. Looks like I’ll have to fire up the crossfire pro, and make new tabs for these with the correct hole sizes.
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[Mac5005]

McMaster-Carr

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I’ve been searching for deals on carbide reamers for common bolt sizes, 3/8, 1/2, 5/8, and 3/4 just haven’t pulled the trigger on any yet. In my limited machining knowledge I would think as long as the plasma cut hole is within the .005” per 1/4” diameter rule for reamers, it would be the best option but I’m open to suggestion from the more knowledgeable machinists.

 

[rockcity]

I’ve been searching for deals on carbide reamers for common bolt sizes, 3/8, 1/2, 5/8, and 3/4 just haven’t pulled the trigger on any yet. In my limited machining knowledge I would think as long as the plasma cut hole is within the .005” per 1/4” diameter rule for reamers, it would be the best option but I’m open to suggestion from the more knowledgeable machinists.

how much kerf is on the edge of the hole?

ive had good luck with cheap jobber drill bits at slow speed run through the holes from the back side of the part where the diameter is smaller due to kerf. I’ve gone through a few bits but it’s certainly cheaper than reamers and if you are good at sharpening and don’t value your time, resharpening one or two bits could work ok.

 

[Mac5005]

how much kerf is on the edge of the hole?

ive had good luck with cheap jobber drill bits at slow speed run through the holes from the back side of the part where the diameter is smaller due to kerf. I’ve gone through a few bits but it’s certainly cheaper than reamers and if you are good at sharpening and don’t value your time, resharpening one or two bits could work ok.

time wise, the current winner is a stone followed by the harbor freight Hercules twist step drill.
The stone removes enough hardened oxide to allow the step bit to actually cut, and is faster/easier than dragging the carbide chisel through it.

I’m ready to send them all back and go get a sheet of 3/16 to cut new stuff but that’s Steve’s call. So far, the response we received was “maybe the zinc coated g8 bolts are oversized”.
The bolts fit inside the heims perfect.

the Minor diameter of the 3/4 coarse won’t fit thru the hole. Fine thread would be worse, and that’s not including the shank of the bolt, which should fit through both tabs and reinforcing plates, if we shank the bolts correctly.
I’ll get some better measurements later today. Didn’t want to yesterday bc I knew it would only make me more frustrated.

 

[Chris_Keziah]

I’ve been searching for deals on carbide reamers for common bolt sizes, 3/8, 1/2, 5/8, and 3/4 just haven’t pulled the trigger on any yet. In my limited machining knowledge I would think as long as the plasma cut hole is within the .005” per 1/4” diameter rule for reamers, it would be the best option but I’m open to suggestion from the more knowledgeable machinists.

Let me know what you find. I was looking at construction style taper reamers for impacts just haven't bought any to try yet.

Digging the chassis. Lack of straight tubes makes it look like a pain to get square but the lines on that thing is tits.

 

[jeepinmatt]

I’m ready to send them all back and go get a sheet of 3/16 to cut new stuff

Honestly this seems like the best option.

Personally, I would contact the seller and say you need brackets that work. That's why you pay extra for a ready-to-go kit. If a couple are undersize, you fix em and move on, but when you're talking 50+ that's a manufacturing defect and quality control error that you shouldn't have to deal with.

 

[Mac5005]

Honestly this seems like the best option.

Personally, I would contact the seller and say you need brackets that work. That's why you pay extra for a ready-to-go kit. If a couple are undersize, you fix em and move on, but when you're talking 50+ that's a manufacturing defect and quality control error that you shouldn't have to deal with.

If I counted correctly, 69 holes have to be drilled out. Most to 3/4, the rest to 3/8. Mostly in 3/16 plate, six 3/8 are in 1/4 plate.

Steve already drilled out I think 12 or 18, in about 2 hr time span. This was to hopefully be able to bolt the bracket kits together to tack them before fitting and final welding.

he stopped once we discovered that’s it’s nearly every hole in every bracket minus about 18 or so ish.

the worst part is we were hoping to get these brackets kits assembled and tacked and fitted so we could build links this Friday with hopes of having a roller with drivetrain next weekend.....

the time loss over hole sizing is frustrating

 

[jeepinmatt]

You should be able to drill them with regular HSS drills, cutting oil, and a nice slow RPM on a drill press, something around 100-200rpm. Do you have access to a beefy geared head drill press with a quick vise? Key is to not let it get too hot, and feed it hard enough that the metal is splitting ahead of the cutting edge instead of dragging across it. And you will take the edge off of the drill every few holes. You know how to sharpen a drill on a grinder or belt sander? This is a great learning opportunity with low consequences, and 3/4" is a pretty good size to learn on or practice with.

This video has very little to do with your issue but is cool enough I'm going to post it anyway:

 

[drkelly]

So far, the response we received was “maybe the zinc coated g8 bolts are oversized”.
The bolts fit inside the heims perfect.

That is a Bullshit answer, WTF?

 

[Mac5005]

You should be able to drill them with regular HSS drills, cutting oil, and a nice slow RPM on a drill press, something around 100-200rpm. Do you have access to a beefy geared head drill press with a quick vise? Key is to not let it get too hot, and feed it hard enough that the metal is splitting ahead of the cutting edge instead of dragging across it. And you will take the edge off of the drill every few holes. You know how to sharpen a drill on a grinder or belt sander? This is a great learning opportunity with low consequences, and 3/4" is a pretty good size to learn on or practice with.

This video has very little to do with your issue but is cool enough I'm going to post it anyway:

I can and do sharpen my HSS stuff but I’ve never had good results with that oxide & hardened area.
I agree should be able do, but I don’t think my drill press runs slow enough or can generate the feed pressure to make it happen. That’s what led me to start with stone to remove the oxide and then finish.

Cool video and makes sense/ reinforces why the cheap Hercules step bit can cut it once we get some bare steel no oxide to the cutting edge itself.

 

[Mac5005]

That is a Bullshit answer, WTF?

I’m still waiting for more details, as that convo is between Steve and Tim. I should know more about that conversation tonight as things can get misconstrued from person to person to person. That little part made me chuckle though, as I went and tried a black oxide, and a zinc f9, and bowmalloy, 3/4 bolt this morning with no success.

 

[Chris_Keziah]

You should be able to drill them with regular HSS drills, cutting oil, and a nice slow RPM on a drill press, something around 100-200rpm. Do you have access to a beefy geared head drill press with a quick vise? Key is to not let it get too hot, and feed it hard enough that the metal is splitting ahead of the cutting edge instead of dragging across it. And you will take the edge off of the drill every few holes. You know how to sharpen a drill on a grinder or belt sander? This is a great learning opportunity with low consequences, and 3/4" is a pretty good size to learn on or practice with.

This video has very little to do with your issue but is cool enough I'm going to post it anyway:

I've done this on a mill however it's very easy to break the tips off of your not careful. I never ran that slow on rpms, I did light pressure with maybe ~500 rpms or so. Really can't remember.

Curious to see how all that mess plays out, one of my most hated things is drilling plasma cut holes.

 

[Mac5005]

I've done this on a mill however it's very easy to break the tips off of your not careful. I never ran that slow on rpms, I did light pressure with maybe ~500 rpms or so. Really can't remember.

Curious to see how all that mess plays out, one of my most hated things is drilling plasma cut holes.

Yep. That’s exactly why I do a test cut first. Check my ipm for the holes and straights so I fine tune the tool path and cut parameters. Also check the diameters so bolts can pass thru and adjust accordingly before I cut the actual.
I always cut brackets with bolt holes first and any supporting tabs, brackets, gussets after so if the electrode and cup erode, the best holes are cut first with a newer tip.

Then if I’m ever worried, it just gets a .250” hole for locating, knowing I have to finish drill to size.

 

[jeepinmatt]

I can and do sharpen my HSS stuff but I’ve never had good results with that oxide & hardened area.
I agree should be able do, but I don’t think my drill press runs slow enough or can generate the feed pressure to make it happen. That’s what led me to start with stone to remove the oxide and then finish.

Cool video and makes sense/ reinforces why the cheap Hercules step bit can cut it once we get some bare steel no oxide to the cutting edge itself.

Free plug for @Junkyard Dog

This'll do it for ya!

https://nc4x4.com/forum/threads/drill-press.200343/

 

[jeepinmatt]

I've done this on a mill however it's very easy to break the tips off of your not careful. I never ran that slow on rpms, I did light pressure with maybe ~500 rpms or so. Really can't remember.

Curious to see how all that mess plays out, one of my most hated things is drilling plasma cut holes.

3/4" drill should be plugging along around 400-500rpm (80-100SFM) in average steel. Throw in some rough, hard edge and you'll want to slow it WAAAY down and it'll still probably die, just less fast

 

[Mac5005]

Free plug for @Junkyard Dog

This'll do it for ya!

https://nc4x4.com/forum/threads/drill-press.200343/

That’s not a Bridgeport, why are you showing me this hahaha. That’s sweet.
I’m trying to convince @ORV design and fab to store his mill and lathe here.

 

[Mac5005]

 

[jeepinmatt]

That’s not a Bridgeport, why are you showing me this hahaha. That’s sweet.
I’m trying to convince @ORV design and fab to store his mill and lathe here.

No sir, that's a by god geared head drill press for real men.

Y'orta getcha one:

So you can do stupid stuff like this with with a 1.5" hole saw:

 

[Mac5005]

On this plate 5 holes are drilled to .419 to allow m10 bolts to pass thru into the heads.
Meanwhile the other three avg .354 as cut and I assume are for 3/8” bolts.

 

[jeepinmatt]

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3/8" bolt should be just under 3/8" (0.375") and the hole should be larger than 0.375". Same for every other size. Theres a whole nother discussion we could get into about ISO limits and fits and hole sizes and tolerance classes and such, but bottom line is the hole should freely accommodate a nominal size bolt unless it was intentionally designed with an interference fit.

 

[paradisePWoffrd]

I was looking forward to this thread, as I have been eying his chassis for a long time. I hate to hear of the issues, and agree that the price should bring quality parts. I would think that he would want to know about any possible issues with the parts and get them fixed asap. I know that I would be pissed too, as I have no time/equipment to properly drill out all of those holes. I would think that most of his target market wouldnt either.

Since you have the parts in front of you, nothing really stopping you from copying them with the correct dimensions; other than spending more money for parts that were already purchased.

Either way, I am following along watching how it comes together.

 

[DannyH]

So I've actually got the same table as Tim does from talking on FB groups, and I would never attempt to do a finished hole on the table. I always 'pop' the hole and then drill after the fact. I do use HSS drills and haven't had to much issues in my delta drill press. I just let the vise float and drill with a lot of force and as quickly as I can. I can usually get about 30-40ish holes per bit and then I grab another because we keep a lot on hand and I do not have the patience for sharpening.

 

[DannyH]

3/8" bolt should be just under 3/8" (0.375") and the hole should be larger than 0.375". Same for every other size. Theres a whole nother discussion we could get into about ISO limits and fits and hole sizes and tolerance classes and such, but bottom line is the hole should freely accommodate a nominal size bolt unless it was intentionally designed with an interference fit.

I can scan a couple hundred pages of my machinery handbook and post them up if you'd like. LOL

 

[Mac5005]

So I've actually got the same table as Tim does from talking on FB groups, and I would never attempt to do a finished hole on the table. I always 'pop' the hole and then drill after the fact. I do use HSS drills and haven't had to much issues in my delta drill press. I just let the vise float and drill with a lot of force and as quickly as I can. I can usually get about 30-40ish holes per bit and then I grab another because we keep a lot on hand and I do not have the patience for sharpening.

I’m not complaining that he doesn’t/can’t plasma cut holes to drop a bolt thru.

my complaint is that he cut the holes, and cleaned them up 15 to 20% of the thickness by some means of cutting. And after doing such the holes are still .010” to .020” undersize, while some holes are completely drilled/milled and fit their fasteners, while some have. .610” hole for a 1/2” bolt.

it’s one thing to sell a kit that’s ready to bolt together, weld, install vs having to drill out 69/80ish holes before assembly, welding, and installation.

another big issue are the poly bushings for motor and trans mount. These are all bushed and sleeved for 1/2” (.493”) bolts while the tabs have a .610 hole.

just a major let down and time waster.

Looks like the current solution is to drill out the holes in the main brackets, and then I’m going to cut new tabs/brackets for all the laminated bolt reinforcement plates, and tabs that the holes are too big for the supplied bolts.

 

[Mac5005]

I was looking forward to this thread, as I have been eying his chassis for a long time. I hate to hear of the issues, and agree that the price should bring quality parts. I would think that he would want to know about any possible issues with the parts and get them fixed asap. I know that I would be pissed too, as I have no time/equipment to properly drill out all of those holes. I would think that most of his target market wouldnt either.

Since you have the parts in front of you, nothing really stopping you from copying them with the correct dimensions; other than spending more money for parts that were already purchased.

Either way, I am following along watching how it comes together.

Exactly!!!

I could cut all new brackets with the same geometry but with correct holes, or just drill the holes out correctly. Both of which are a time waster after buying the modular kits with the intention of being a time saver.

I’m not one to directly copy someone else’s work, that’s just not me. If I like something enough to copy it, I’ll just buy theirs and save time, and support them / their investment.

the entire undertone of this build for Steve was to do it nicely/clean with an emphasis on quick.

Despite having a bender, notcher, cnc plasma, etc we thought it would be best to buy a buggy in a box with as many cad designed parts that would work well to save as much time as possible, while still fitting into the budget.

The fully assembled and welded chassis in a weekend proved that is a viable concept, just the plate work is a clear flop.

it’s not going to stop or stall us, just delays that kill the initial vibe and high we were riding from going from pallet to chassis in such a short time.