Jump to content

Nominations for Tractor of the Month
Garden Tractors and Parts on eBay



Photo
- - - - -

Mid Travel Suspension Mod - Tow Behind Sprayer


  • Please log in to reply
40 replies to this topic

#16 Chi11iwack OFFLINE  

Chi11iwack

    Member

  • Member
  • Member No: 4194
  • 1 Thanks
  • 18 posts

Posted June 19, 2011 - 02:37 PM

I started in the shop and got the other trailing arm done, no pic - it looks just like the other one lol.

I needed to get figuring on how I'm going to suspend this thing on the springs, first thing I had to do is find out how "strong" the pair of springs I bought were. I measure the resting length of the spring at 4", I then hung a 5 gal pail of motor oil (36 lbs) from it an measure the length as 7". So the spring constant is 12 lbs/in. How did I figure that out?

My daughter (11 yr old Grade 6) has been watching what I've been doing, so when I started my figuring I decided I would teach her some simple algebra and physics. She's a keen student (proud Dad here) and has a great appetite for knowledge. I have this cool digitial pen that records what I sketch in a special notebook and then uploads the notes into the computer. I used it and here's the two pages from her physics and algebra lesson.

Posted Image

Posted Image

I had a bell crank style suspension in mind pulling on a regular spring, so I had to figure out how long the lever arm connected to the spring would be compared to the trailing arm length. Also to consider is how much wheel travel I wanted to allow (6") and how far I would need to stretch the spring etc... I just used 10" for my trailing arm length although I haven't measure the actual length. I'll do that, then substitute that number back in and see what comes out.

Summary, I need to use two springs like these ones on each side and they are mounted about 6 5/8" from the axle. Sounds good right? Wrong! This means at full load, the sprayer is back at stock ride height!! Then slowly goes up to 6" higher as it empties... I need a lot more spring rate to try and limit the full load travel to maybe 1/3 the overall travel or 2". (That's a rule of thumb I remember from dirt bike suspension setup).

Running the math again with that fact yields an 11 1/2" long lever arm for the spring... OK, need heavier springs or it won't be compact enough. Problem is, they don't print the spring constant on the stupid packaging so it's trial and error.

Alright, just ran some more numbers. If I arbitrarily decided I wanted a spring lever arm of 3" only and I wanted just one spring I would need a spring that would have a coefficient of 350 lb/in !! It would only need to stretch 5/8" to be balanced. Working even further backwards I find that this spring would only stretch 0.102" when my pail of oil hangs from it. SO! I'm going back to my hardware store tomorrow with some rope and I'm going to be picking up a 5gal pail of oil with different springs until I find one that is pretty short and stretches less than 1/8" when I pick up the pail. :D

Posted Image

Maybe I drank too much coffee today...:rolling:

Edited by Chi11iwack, June 20, 2011 - 11:53 PM.
Make scribbles even bigger


#17 NUTNDUN OFFLINE  

NUTNDUN

    Lost in Cyber Space

  • Admin
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 3
  • 10,266 Thanks
  • 15,618 posts
  • Location: Pennsylvania

Posted June 19, 2011 - 02:53 PM

I am glad someone here understands all that scribble because I sure don't LOL

Glad you are getting close to getting it narrowed down. Are you going to also add shocks to dampen it some or no need to worry about them?

So, are you going to make a whoops section and maybe a table top to test her out on?

#18 RickC OFFLINE  

RickC

    New Member

  • New Member
  • Member No: 4231
  • 0 Thanks
  • 3 posts

Posted June 19, 2011 - 08:22 PM

Nice work.

#19 Chi11iwack OFFLINE  

Chi11iwack

    Member

  • Member
  • Member No: 4194
  • 1 Thanks
  • 18 posts

Posted June 19, 2011 - 10:57 PM

<snip>
Are you going to also add shocks to dampen it some or no need to worry about them?


I had thought about grabbing some gas shocks from the auto wrecker, the kind that help open hatchbacks or hoods etc...


So, are you going to make a whoops section and maybe a table top to test her out on?


Now that sounds like fun!

#20 KennyP ONLINE  

KennyP

    FORDoholic

  • Super Moderator
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 2253
  • 28,458 Thanks
  • 39,687 posts
  • Location: Collinsville, Oklahoma

Posted June 20, 2011 - 05:28 AM

Glad you have it all working out. Good luck on the spring.

#21 jj69chev OFFLINE  

jj69chev

    Tractorholic

  • Senior Member
  • Member No: 626
  • 24 Thanks
  • 150 posts
  • Location: Big Lake, MN

Posted June 20, 2011 - 07:26 AM

:welcometogttalk:

I noticed that he sharpened his tungsten with a long gradual point and had it sticking out quite a bit away from the tip. I tried that and lo and behold, success!! My arc stopped wandering all over and my tungsten stays sharp (if I can keep it out of the puddle - doh!). I still have lots to learn, and need a lot more practice yet. :)

I sure like the tig, no slag to clean up like the stick welder.


I love TIG welding, and may have to look into one of those welders. As you said in TIG welding tungsten must always be sharpened. The only exception is if your welding aluminum, the you need to melt the tungsten into a ball tip. Your welds and progress look good by the way keep up the good work!

#22 RustyTub OFFLINE  

RustyTub

    Tractorholic

  • Senior Member
  • Member No: 2702
  • 25 Thanks
  • 137 posts
  • Location: Southern Oregon

Posted June 20, 2011 - 10:52 AM

You Want to Sharpen your Tungsten into a point for sure, But you want to grind your point holding the file, grinding stone or in my case a 1" belt PARALLEL to the tungsten. If you hold it at a 90* angle from the stone and grind your point. you will get the wandering affect. With the Machine Setup properly you should not have to regrind your tungsten unless something screwed up. Been quite some time since I ground mine.

There are different color codes of tungsten. Here is just a bit of basics,

2% Thoriated color code red, This rod operates below its melting point. Thus being able to hold up better. This is your most common Tungsten. mainly used is Stainless or Mild steel. (pretty much if you weld on DC you should be using RED.)

Next up is Green, This is 99.5% pure tungsten it is not as strong as of alloy forms of Tungsten electrodes. It is also the cheapest and also the quickest cunsumable electrode. Green operates above its melting point providing that nice little ball tip. This is what you should be grabbing for Aluminum and Magnesium welding.

I think there are 4 other types of electrodes but those are more specific job related and these are the two most TIG owners will every use.

Another side note is I use one belt sander for tungsten grinding ONLY this makes sure I have no Cross contamination in my welds.

The more time you get under the hood the better I love welding it is a great therapy for my self.

Also you said you dont have a foot switch might want to see if you machine is compatible with a foot switch you can pick those up pretty cheap. I run a foot switch or a thumb reel. it all depends on what I am welding if I weld on the bench it is a foot switch but every thing else I love the thumb reel allows me to be a bit more stable while welding instead of have a foot controls the switch.
  • NUTNDUN, coldone and Chi11iwack have said thanks

#23 RustyTub OFFLINE  

RustyTub

    Tractorholic

  • Senior Member
  • Member No: 2702
  • 25 Thanks
  • 137 posts
  • Location: Southern Oregon

Posted June 20, 2011 - 08:31 PM

Also if youare using a small diameter electrode you can use brown. It is an alloy form, forget off hand the make up but it handles ac welding very well doesnt spit. And retains a ball tip very well. This is great for thicker aluminum welding jobs as it will last longer. Although you cannot use this for dc welding.

#24 caseguy OFFLINE  

caseguy

    Connoisseur of Rusty Junk

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 906
  • 1,624 Thanks
  • 5,600 posts
  • Location: Edinburg, PA

Posted June 20, 2011 - 09:12 PM

:wave: Chi11iwack Welcome to GTTalk! I'm glad that you've joined us and are giving us all some lessons in critical thinking! Great work so far on the sprayer. I'll be watching this thread for more progress! Keep up the great work!

#25 Chi11iwack OFFLINE  

Chi11iwack

    Member

  • Member
  • Member No: 4194
  • 1 Thanks
  • 18 posts

Posted June 20, 2011 - 11:03 PM

Thanks for the warm welcome fellas and all the kind comments. I'm having fun with this and it's good to share it with some others that won't think I'm totally insane. LOL

With the Machine Setup properly you should not have to regrind your tungsten unless something screwed up. Been quite some time since I ground mine.


Funny, I used to have to sharpen it every couple welds and now I've managed to keep it pin sharp without putting it to the stone once in the last two days!

I use a bench grinder with a stone dedicated to the tungsten so I don't get contamination, and yes I sharpen parallel to the point. I'm using the red band which seems to be working very well, good thing cause that's all I have. When I bought the welder, I also bought supplies from the same guy at the same time. I was worried that I may not be able to get them locally so I loaded up.

My machine is DC only, so I won't be doing any aluminum. I'd like to get an AC/DC machine though...

The more time you get under the hood the better I love welding it is a great therapy for my self.

I do feel like my skill is improving quite quickly, and I want to just hang out in the shop and glue steel together all day! But work and life are foiling my plans! My machine will work with any switch, but there's no foot pedal current control supported. That would be the cat's ***, sometimes I think "whoa, just a little less heat would be good" and it would be nicer finishes on the tail end of the weld too.

I did manage to get some more progress. New post coming up in a minute. With plenty of weld pr0n!

#26 RustyTub OFFLINE  

RustyTub

    Tractorholic

  • Senior Member
  • Member No: 2702
  • 25 Thanks
  • 137 posts
  • Location: Southern Oregon

Posted June 20, 2011 - 11:12 PM

It is so nice to be able to roll backthe heat at the end of your weld and hold your post flow shielding gas over the weld as it cools. Keepyour eyes open I got my last tig for cheap from a shop that was updating their euipment. I have since sold that and have been running a thermal dynamics machine. I sure got spoiled with a water cooled torch.

Progress looks cool may have to borrow your formulas to build something. Dont know what but I sure like the math involved.

#27 Chi11iwack OFFLINE  

Chi11iwack

    Member

  • Member
  • Member No: 4194
  • 1 Thanks
  • 18 posts

Posted June 20, 2011 - 11:13 PM

Well, I got a little impatient with waiting to go look for a spring and decided to try and mount the finished arms onto the axles anyways. Only, instead of springs supporting them I just drilled a hole through them and put a pin through to hold them rigid.

The axle comes welded to a piece of sheet metal and that sheet metal is bolted to the underside of the trailer. This is a bit of a "suspension" for the stock system because the sheet metal is at a bit of an angle and it flexes with load.

Here's a pic of the arms mounted that's a little out of sequence but it shows what it looks like. You can also see the square hitch spacer that I will go over a little further down this post.

Posted Image

and here's that sheet metal suspension thing underneath the trailer.

Posted Image

Of course, the load on the axles has some leverage now with the trailing arms so when I put some weight on the trailer (just a little) the sheet metal just folded. So you can see I have added some gussets to help the sheet metal resist the torsional load placed on it by the rod axle. I put two on this side shown above and one more on the other side.

Posted Image

As you can see, welding in a straight line is much easier than welding on a small circumference tube!

The problem with jacking the back end up is that the dip tube for the pump is in the back and all the water/chem ends up in the front. So I needed to fab a spacer for the hitch to bring the front end level back up level or a little higher than the back.

I took some 1/4" flatbar and marked out the dimesion of rectangle I needed then used the zip-cut on my grinder to cut partway through the flatbar (most of the way actually) at each line I had marked. Then I just easily folded it into the rectangle by hand and welded it up.

Posted Image

Posted Image

Yeah I know it's a good "root pass" but could use a second pass to build it up to full strength. I didn't bother since it's already waaay overbuilt.

I then used the drill press to match drill a couple holes in the rectangle for the hitch to bolt onto, and then assembled the whole thing again. It was much stiffer now and seemed to rebound from the weight better. So I wheeled it over to the barn and filled it with water. Before I did I measure the rear clearance at 10".

Posted ImagePosted Image

And then full of water it was down to 8 3/4"... uh oh.
Posted Image

So I took it for a little drive slowly and just a few little bumps. came back to the same spot in front of the barn and measured again.

Posted Image

6 1/8" !!! FAIL !!!:wallbanging:


So I emptied it back out and before the water had finished draining I had already sketched up my new solution on the shop floor with a soapstone, and began cutting some steel...

<More to come>


#28 Chi11iwack OFFLINE  

Chi11iwack

    Member

  • Member
  • Member No: 4194
  • 1 Thanks
  • 18 posts

Posted June 20, 2011 - 11:18 PM

...
Progress looks cool may have to borrow your formulas to build something. Dont know what but I sure like the math involved.


Thanks! My daughter found it an sort of interesting lesson. I should put it in a spreadsheet for re-use. That way I don't have to derive it each time lol. I haven't totally abandoned the spring idea yet, just giving torsion bars a little trial and error time since the formulae I found for Torque generated by angular twist of a steel rod wasn't very straight forward. I'm going to keep looking though.

Cheers!

#29 Chi11iwack OFFLINE  

Chi11iwack

    Member

  • Member
  • Member No: 4194
  • 1 Thanks
  • 18 posts

Posted June 20, 2011 - 11:49 PM

What had happened is that the 5/8 rod twisted and bent a little between where it mounts to the sheet metal plate underneath and the the trailing arm. If that distance was shorter it probably would have been fine. I got thinking about a stouter torsion rod and housing and went to the "steel rack" and grabbed a piece of 1 1/8" .065 wall round tube and cut it the length of the other axle minus the 5/8" stub lengths.
Posted Image

I have a milk crate full of these pins of various sizes from industrial conveyor chain from my bro in law.
Posted Image

They are the same ones I used for the axles on the swing arms. They are a little rusty and covered with mill scale, but the wire wheel on the bench grinder has them shiny is seconds. Look at the difference!

Posted Image

So take the nicely cleaned 5/8" "pin" and put it in the vice and stack the 1 1/8" diam tubing on top of the "pinhead". Conveniently the tubing is just a hair smaller than the pinhead.

Posted Image

Then it's just tack in three places on the circumference so it doesn't lift one direction or the other and weld it up!

Posted Image

Once I welded the other side on, I needed to start work on a small plate for each side to I could bolt the assembly onto the trailer. It's kinda hard to explain so it will reveal itself as it gets built.

The base of the trailer is shaped like a triangle, narrow at the front. So where the new axle crosses below the base it's not 90°, it's some other angle... So I got my angle finder and "measured" it.

Posted Image

I will use that to align the tabs when I weld them to the axle. This way the tabs will mesh nice with the base so it can just bolt on.

Posted Image

That's all for tonight, you're all caught up. I'll hopefully make some progress tomorrow after work and get it posted. Thanks for coming along for the ride.


#30 RustyTub OFFLINE  

RustyTub

    Tractorholic

  • Senior Member
  • Member No: 2702
  • 25 Thanks
  • 137 posts
  • Location: Southern Oregon

Posted June 20, 2011 - 11:54 PM

A spreadsheet would be sweet. I am always thumbing threw my notebooks, I make my notes in different note books for furture references.

So where was the failure did the oe axle mount that you stiffened up bend? You are killing me not knowing were the failure was.

You have quite a bit of leverage out there with your trailing arms, I am thinking your spring setup would work best. With a fair amount of reinforcing on the oe axle. But I am sure you will surprise us with another idea. I love trial and error and real world testing.




Top