One thin mint...

The last three evenings have been "testing" mode.  Yes, it is basically done.  Always room for improvement, though.

Day 1:

First trip out, no blade.  Drove it around the yard to get the feel of it and see if it would dig up the grass with the tank steering.  Good news, handles well, good speed, doesn't dig the grass up unless you make a really tight turn or a "sit and spin".  Back to the garage for the blade.  Oops, wait, one of the wheels is coming off, make that three.  The bolts weren't tight enough.  Found the bolts with magnet bar, put them back with double nuts (jam nuts).

Installed blade, stand back - way back, start - no flying death!!!   Cool.

Down to the hill which is sorely in need of mowing:

Observations

• Grass is tall, mower doesn't bog, clog, or toss huge clumps.  Not bad for never having designed a mower deck before.
• The pic above shows the engine on the downhill side.  There is only about 1/4 tank of gas and mowing uphill starved the carb of fuel.  Gravity feed doesn't work too well, may have to add a raised aux tank.
• The two large group 24 marine batteries are HEAVY, about 44 lbs each.  The design put them in the back over the two axles being careful not to create an overhang.  In CAD, everything was flat and level.  Running uphill at about 45 degrees, a sizable fraction of the rear battery is behind the rear axle and the CG is probably above the axles to start with.  On the slope, goosing the throttle or stopping quickly going downhill causes the front to rise slightly - or generally more than I'm comfortable with.
• Alternator belt needs tightening, old school, no spring tensioner.

Back to the garage.  On the way, can't resist doing a spin move in the gravel part of the drive - wheeee!  Crap, another wheel is coming off.  Wait, the nuts didn't come loose, the bolt sheared off!  Purposely used ungraded fasteners to preserve axles in case of high stress, but apparently a rough turn is enough to trip these shear pins.

A link to maiden voyage ( ignore belt squeals please ) - YouTube Video

Day 2:

Replaced all wheel bolts with Grade 5 hardware.

Tightened up the belt a little more.

Added 40 lbs of ballast to front of mower ( eight 5 lb barbell weights left over from son's high school football weightlifting years )  Tie wrapped on temporarily to test.

Back to the hill, loosing daylight, but had to try it out.

No broken parts, balance is much better, no more belt noise, adjourn to the garage and call it a success for the day.

A little research in the late evening on alternate solutions to weight distribution and ballast mounting options.

Day 3:

The evening prior, I was looking into smaller batteries.  The two marine batteries were originally intended to power the machine without an alternator for about an hour.  Since I had already bought them and didn't think the weight was an issue I used them.  However, since I chose to do the alternator anyway, I didn't really need that deep of a reserve.  I need to run the mower on electric only out of the garage, down the drive and down the hill before I start it - maybe a 800 ft or so.  Likewise I need to make the return trip, especially if I run out of gas.  Even so, I should be able to do that if I consider the mowing time is essentially free, Amp Hour wise.

I thought about ordering some gelled electrolyte cells, but they generally require low current charging and aren't well suited to alternators.

Then it hit me, lawn tractor battery.  They are just mini car batteries essentially, and are widely available.  Most auto stores carry them, but mostly in a 280 CCA size.  Turns out Tractor Supply has 420 CCA ( U1 size ) batteries for about $50 each.  Two of them are smaller than one of my group 24s, and shorter, and less than half the weight.

Picked up two on the way home, and mounted them up.  I used a piece of wood to space them forward and keep them there.

Removed the front ballast and here we are:

Return to the test hill and finish mowing before the rain?  Sky looks a little dark.

Observations

• Mower is peppier with the reduced weight.
• The front end is still a little light, so will probably add maybe 10 lbs  to the front to help reduce scary behavior.  It is *way* better than before, able to tackle even steeper sections than previous day with only mild moments of panic.
• May also help to increase air pressure in the tires to reduce bouncing and squatting under weight shifts.
• Filling the gas tank all the way full allows full inclined mowing in the proper forward direction ( favorable to avoid oil loading the backside of the piston if oriented downhill )
• I really need to program my radio transmitter to correct for the proper stick direction for forward/backward and left/right.  Both drive channels are backwards making steering interesting.
• No issues making it back up hill on electric only with smaller batteries.  Voltage starting was 25.6 V and 25.4 after I returned and let it sit for a bit.  Overall it is not severely depleting the charge.
• Motors were not hot, nor were any of the cables.  The fan on the motor controller has not yet tripped on, shows the controller is comfortable with the current demands.
• It's kind of nice standing 10 or more feet away from a mower.  My clothes stay clean and I'm not getting grass pollen and dust all over me.  My allergies will thank me.

Mechanical Done*

Dare I say it?  The mechanical is "done".  Note the * for the footnote, which could read "mostly" or "i think so"...

It's harder to spend the time inside with everything *spring* going on, but it's been cold these last few days and the hill grass is growing like crazy.

Mostly pics today, but hopefully start seriously wiring tomorrow?

 Belt Guard from underneath

 Belt Cover ( currently not installed, needs tweaking, will see if needed )

Sheave and Belt installed ( taken from underneath up on jack stands )

Rear Chute with Side Baffles installed ( keep grass out of chains )

Rear View with Batteries and Motors reinstalled

Side View showing electronics enclosure mounted

Custom Alternator Tensioner (Aluminum rod, Heim Joints, Jam Nut)

Thinking about how test the motion, I would have to put the whole thing up on blocks or risk it climbing a tree or worse.  Then, a simplification - just remove the chains from the motors to the main driven gear ( or in this case - since I just put the motors back on - don't put the chains back yet )  Now it won't go anywhere and I can test the radio and everything else safely.

Things to remember:

Don't forget to add oil to the new engine!

Check gears, bearings, sprockets for tight set screws.

Now, where are those wire strippers...  

A Rim for the Deck

OK, maybe a little paranoid, but better safe than sorry.

The deck is made of 16 ga steel, about 0.060" thick.  Some commercial decks are 10 ga ( ~0.130" ), but I didn't want all that weight.  A compromise is to strengthen the bottom edges with a strip, I used two pieces of 1 inch 12 ga ( ~0.104" ) steel.  One piece goes all the way around, about 5 ft long ( 22 inch diameter - chute width ).  The second piece is only 3 ft long and covers the front half, 3 o'clock to 8 o'clock.

Clamps!!!

Bottom side tack welds

Topside/Outside View

The straps were wrapped around a steel disc about 20 inches in diameter and persuaded with a large hammer to stay curved.  The million clamps were needed to hold the strap tight all the way around with minimal gaps while welding.  Each ring was tacked separately every few inches.

This combo nets about 1/4 inch of steel in the front and sides, plus about 3/16 everywhere else.  This should provide substantial insurance against errant dings.

It started to rain while I finished the welds, so the paint will have to wait.

A little more grinding, welding, drilling ...

Last week I was out of town for a few days, but since the weekend was cold I managed to make some decent progress here and there.  Last post had the deck mocked into place, with a claim of a plan of attack.

The deck is basically finished, mounting holes in place (3/8), plus the alternator mounting completed.  In the following shots you can see the detail, plus a few large dents.  Not sure if I mentioned it, but to get full clearance at the highest deck height a little hammer adjustment was needed.  The design height is about 3 inches, but I can get 4 out of it with the sheet metal massage.  The dents clear the bearings and the sprockets with plenty to spare. 

The alternator pivot bolt has the upper diagonal piece welded to the bottom plate so the alternator doesn't tip under belt tension.  It will be clear once I share an assembled photo.  Not shown in the unpainted pics is a block that anchors the belt tension adjustment.

 View of deck showing mounting tabs and alternator support

Rear View of Deck - Shows 1/4 in. rod brace and aluminum frame tabs.

Step Washers

Above is shown the step washers I made.  The holes in the deck were cut to 1/2 inch, which I misread from the engine drawing.  They are supposed to be 3/8.  I didn't want the motor to shift sideways - ever - so I debated welding the hole smaller or making these.  Welds are hard to drill and they are perfectly centered now, so this seemed the most accurate, albeit the most work.  The center boss is 0.050" tall as the sheet metal is 16 ga.  The OD is 1 inch, and they are about 0.150" thick to allow better oil filter clearance as well ( it's a feature, not a mistake... ).

A different angle with a little paint applied

The rear battery tray, done.

The battery tray also needed to be adjusted to fit the alternator, by about 2 inches.  The semi round mod can be seen above in the photo.  Also shown in the photo is the central lower crossmember notched.  To the immediate left and right of the notch can be seen the two rear deck height adjustment bolts.  Two more bolts go through the front brackets ( second photo above ) to the deck tabs there.

The mod of the tray involved cutting the front lip in half and partly off, bending them inwards, cutting the round piece out of the bottom, bending the lip back and splicing a section in the middle to keep it rigid.  The whole mess was welded together and ground smooth.  It is hard to tell it wasn't that way to start.

The deck isn't back in because I am debating adding a ring of metal strapping around the bottom rim of the deck to reinforce it.  I was looking at a commercial mower that had a similar feature and it might be handy to prevent bending the lip into the spinning blade if I hit a rock or a small stump.  I didn't paint the bottom edge of the deck in anticipation of adding this, plus I ran out of paint anyway.

Best laid plans...

Spring is here, or at least it was.  The temporary warm spell has been replaced by snow and 30 deg weather.  Spring yard work took priority over recent history - mulching, raking, putting the plow away ( oops? hopefully not ).

Mounting the deck - Last post was the basic deck fabrication.  Adding a cutout for the alternator mounting necessitated another frame modification.  Initially I had planned on skipping the alternator and adding it later, as such I hadn't put the detail into mounting it.  Coupled with not having made a decision on exactly how to mount the deck, or whether it was going to have adjustable height or not - led to a lot of thinking, not too much progress.

So, here is the result of the thinking, not quite done, but there is now a plan to follow.

On the deck, there are four mounting points tack welded for alignment.  One on each side in the front and two in the back.  The rear ones will double as alternator mounts and there will be hanger bolts drilled through the middle crossmember.  In the front, there will be two tabs made to hold the same type of hanger bolts.

Since the alternator wants to occupy the same space as the middle cross member, I need to cut it - about six inches worth.  To avoid weakening the frame, I decided to add a replacement cross member up about 10 inches higher than the rest of the frame.  The uprights are 1/4 steel plate 2 inches wide.  They are repurposed from a driveshaft safety loop from my son's car ( a former race car ).  It was almost perfect, only a little tab needed to be welded on at the bottom to make it fit the bolt spacing.  At the top is another piece of 1 inch tube, and if you look close you can see the temp bolts are wayyy too long ( ran out of short bolts - HW store roadtrip... )

You can also see the marker outline of the engine projected onto the deck.  This was used to help with the location of the tabs and the alternator *AND* to help avoid stupidity if I'm not paying attention to interferences.

The crossmember's extra stiffness may not be necessary, but it also provides a potential mounting for the electronics.  They will be in a plastic enclosure for radio reception, and up high will allow for better performance and ease of access.  Later...

Spring is in the air...

The promised deck info post.  Back a couple weeks ago when I posted the redesign of the frame to accomodate the deck, the reason was the sheet metal detail was completed.

At one point, I had thought of repurposing a deck just to get everything going, but the mods to a rusty nasty deck would have been more extensive than just going from scratch.  Also, the thought of cutting all the sheet steel with a sawzall was less than motivating.  Instead, I took the CAD drawings and sent them to a local shop I found on the internet.  They came back with an extremely attractive quote to laser cut them, including material for $50.  It took a couple weeks, but the quality is outstanding.  They are in Lima, NY and are very easy to deal with.  Nice folks too.

Smidgens Inc

I sent them a DXF of what I wanted in 16 ga steel, no need to worry about layout as they optimize it automatically.

Here is a shot of the battery tray and a couple of pieces for the belt guards.  The flat piece shows the slots cut in to facilitate bending without a brake.  The small guard is shown after bending in the vise by hand.  A few tack welds will hold it well.

Here is a shot of the underside of the mower deck.  The two hoops were bent by hand and tacked together, then the bevel was attached to the top by tacking on the inside and running a full bead around the outside ( you can see the HAZ ).  The lower rim is tacked on, but not yet fully welded.

Here is the (mostly) finished product.  The lower rim is fully welded, both joints are ground smooth.  The exit chute is also formed and welded on.

Next up are the belt guards and mounting the alternator.

After painting, the wiring comes next and we're getting very close...

Yes, we are still here...

My last post was in January and it is now March.  A lot has happened, but nothing has yet been shared.  There should be a few catch-up posts this week or so.

Upcoming posts:
1) electrical progress
2) mower deck details

Over the last week, there was a slight design change.  After finalizing the deck detail, a few frame elements needed to change to make everything fit better.

The front cross member needs to move forward and since today was relatively nice out ( 40 and "sunny" ), it was easier to make a mess out in the driveway than in the garage rough cutting the aluminum stock on the saw.

Frame as it was originally

Fabbing the mounts ( note that with the DRO there are no setup lines on the parts and it is *way* easier and faster to make stuff like this ).

New frame mounts with crossmember moved forward to clear the deck.

Still need to trim the axles a bit shorter as well, but that's all for today.

A little clarification on something I mentioned in a previous post, and a little humor.

I mentioned that the part numbering on these JS46 mowers was a little bizzare.   Turns out there are two things happening with this model.

First, it is sold as a John Deere, but it appears to be manufactured by Murray.  Probably them's fighting words to people that bleed green, but it doesn't make any sense it would be the other way around.  I'll show why later.

Second, pay attention to the mower serial number.  There is a breakpoint before or after 150K ( 150,000 ).

Early models use the GX22837 blade adapter with a GX23522 blade (one holer).
Later models use the GX24214 blade adapter with a GX24213 blade (three holer).

early:

 

Late:

 

Note that I could not find a picture of the GX24214 anywhere, these are pics I took.  I think this part is top secret or something, very odd it is that hard to find.

Both adapters are about $10 each, and the blades are about $30 online.  Interesting, though, the early blade 23522 is available at Lowes for $19.  No where on the package is indicated it is only for early mowers.  Curious.  Par for the course there.

Back to my second point.  Murray.

The numbers on the blade adapters, early 7101414, late 7104332, and on the blades early 7104179, late 7103288 are Murray numbers.  Strictly they may be AYP or even Briggs, as these parts all came in Briggs boxes.  However, they are made in the USA.  

At any rate, why go to all this trouble?  Like I said before, it is easier to find parts for a model of a mower if you know what you have.  JD has a reputation for maintaining supply and their dealers are quality.  Many home store blades are crappy thin and often bent.  these blades are SERIOUS, almost 1/4 inch thick.  They will be much easier to sharpen.

The lesson for today is - if you are looking to buy a mower or any piece of equipment, get the model and search for the parts you might need in the future.  You may learn something about the unit you intend to buy, or maybe that it isn't exactly what you think it is after all.

Progress at last...

After non-trivial searching for parts, I settled on mower blade, adapter and pulley from the same Deere series mower that the engine came from, a JS46.  I ordered them online as that is way cheaper than visiting the local dealer (sorry).  HOWEVER, what wasn't clear is that there was a serial number breakpoint where the blade & adapter changed designs.  I ordered the correct adapter, but the "cheaper" blade had to be exchanged for the right one.

The earlier blade only had one hole, the newer one has three as shown above.  In the diagram (from partstree.com), I chose the 0050 pulley and the 0110 blade adapter to fit.

This is important as the blade adapter mounting surface is 0.9 inch lower than the end of the shaft, and the blade itself has the cutting edges even lower again.  This results in the cutting plane being 1.65 inches beyond the end of the shaft.  This folds back into the deck design and defines the height of the motor mounting with respect to the lower edge of the sides.  Now that part can progress forward.

Additionally, I acquired a Spektrum DX7S radio and AR8000 receiver.  Local purchase at Performance Hobbies in Webster.

I was going to get relays from the same place I got the motor controller, but I need at least 3 channels ( I ordered 4 ).  They wanted about $25 each, so I looked around a little more.  I found Pololu ( same place that makes all kinds of stuff including some of the original RepRap motion control ) had some nice units for under $10 each.  I also scored some RC servo cable extensions.

These relays will control the engine start and kill switch plus the motor brakes.  These modules interpret the RC servo pulses and turn on the relay at a certain threshold.  At this price, it isn't worth making anything.  A very rough draft schematic is below.

I am looking at circuit breakers and will probably use a Bussmann 70A switchable unit, which will double as an "off" switch.  I may also add some automotive self resetting breakers here and there as I worry about melting things sometimes.

Still working on tooling, the Y axis DRO is getting closer.  The encoder mounting plate is done, and working on the bracket for the read head.  The new vise is installed and trammed in, what a difference that makes in setup and repeatability!

Progress Update

Yesterday, the Briggs engine arrived via a very mixed up FedEx delivery.  Also, I picked up the special order 24 Volt alternator at the local electrical shop.  They installed the bidirectional fan and put the smallest diameter pulley on that they had in stock.  Normal is 2.5 inch diameter, but they had a 2.25 on hand.  They said for best output I should spin it at 4500 RPM, but with a 2.85 drive pulley I should get close to 4000 which is pretty close.  I can change the pulleys later if the load balance doesn't quite work out.

Further progress is temporarily on hold.  Today I installed the X axis DRO on the mill and also received my new used Kurt D675 vise.  I cleaned the machine to install the encoder, and also installed the new vise.  It is much more robust than the older Armstrong that I got with the mill.  I just need to tram it in, maybe tomorrow, then I would like to install the Y axis encoder to complete the DRO.  I also have a Z encoder for the knee, but I'll save that for another day.

These upgrades should allow for easier and more accurate fabrication of remaining parts.

L8R...