iDRY Vacuum Kilns

Sponsors:

issues with the electric clutch on the home built slabber

Started by shelbycharger400, January 03, 2012, 10:32:46 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

shelbycharger400

well to summarize what i have going.  i have a 12.5 hp briggs,  had a 4 inch pulley elect clutch, went to a 6 inch pulley electric clutch,  belt to jackshaft with a 2.5 inch pulley, bottom of jackshaft is a chain saw sprocket tig welded on . jackshaft is a 1inch , bolted on with 2 pillow block bearings.  chain and bar is a stihl 36 inch.
First setup i had the bar straight across, then few days ago i angled the bar, angling the bar with running standard chain seems to run a bit faster.   cutting any log wider than 8 inch diameter, the clutch periodically slipps then i have to stop and get it spooled up again,  here its running around 8,000 rpm.
good battery, charging at 13.7 volts.. put the meter on it, after ripping slowly through a log one foot long, bat is at 12.7  quickly jumps back up after clutch is off .   this is a lawnmower style.
Im seeing what you guys think, considering a mechanical tensioner for the belt drive,  or just going full hydraulic at this point,  im irritated things are not working well.  I could go direct drive, but i dont like the idea of shutting it off every time i need to adjust something.      i have seen a few videos of direct drive saws,   not shure if the lucas dedicated slabber is direct drive or not .    Let me know what you people think.    my max width on the chassis is 28-29 inches..   id like to do it.

fishingmike

I built a slabber a lot like yours. 15.5 hp Kohler electric clutch over to jackshaft and saw sprocket welded on.  I had a lot of problems with the clutch not being able to handle the load. I ended up replacing with a double groove 5 in pulley on the engine and a 2.5 in pulley on the jackshaft. The bar is a 36 inch. Mine is mounted straight across so I can get about 35 inches of cut. I thought about putting it on at an angle to speed up the cutting but did not want to loose any width. I ground off half the cutters so that there is more power going to each cutter. Made a huge difference. Sped up the cutting by almost 3x. As far the clutch goes, I would toss it and go to a solid pulley with an idler to engage it. I will get some pics up in a few days so you have a better idea of what I am trying to say.

Hilltop366

I think fishingmike has got it right, it seems you have exceeded the limits of the clutch, I never had much trouble with the clutch slipping on mine only because the belt would slip first, in the planning process of making mine I went with the theory of slower is better and gave up on thinking chain saw speeds, it took me a while but my theory is that the only good reason a chain saw spins the chain that fast is because it has to in order to make enough power and be light weight, In our case of using much larger 4 cycle engines (I used a 16hp twin Briggs) weight is not a issue, and things turn much slower so to keep cutting speed up I use 50 thousand depth on the rakers, and like fishingmike mentioned a full comp chain really pulls a lot harder as well. Also there is a power loss and a lot of extra wear on the bar and chain by turning things faster even before the cutters are in the wood. I am not sure where the limits are in slowing the chain down and increasing the depth of cut but I would be tempted to try a 4000 rpm jack-shaft speed and see what happens.

shelbycharger400

when i had the 4 inch pulley, it cut wayyyy too slow.  the chain im running  is an unmodified 3/8 , without the anti kick back bumpers. its still factory grind. I did get some flac from the dealer, until i told him what i was doing with it. Thing i like most is that dealer, they say minimum on hand stock quanity is atleast 3 bars and 3 chains for 36 inch. If i went with a bigger bar, say 42 or 48, they would have to spool a chain up.  i researched it a lot before i built this machine.  somewhere on the forum i read a "book" it went into detail on shearing of the wood fibers.  this gives a calculated 6000 rpm or was it feet per minute, cant remember.  A machinist buddy of mine (lives in maple grove/dayton) anyway... kurt helped me calculate the numbers, from every equation,  cutter tooth, engine rpm, sprocket teeth, in feet per minute i i recall.

I need to get a new camera, but the bar im using has a replaceable tip,  just before the rivits , kurt drilled in a  3/8 hole, just so it broke through the guide rail where the chain runs through. read this material is harder than nails, he drilled/ milled this bar on the bridgeport. I found some push lock bulkhead fittings, from a place called d+s machined products, (maple grove address, but in osseo). so kurt  drilled a .050 hole in it, and i double nutted it on both sides and made shure the hole lined up with the slot.  i used a 4 inch piece of 3/16 hose, then a few fittings up to 1/4 tube, and plugged the other end of the fitting. It oils somewhat ok, but i should have just used the 1/4 pushlocs i got. Fastenal had the 1/4 ones, but i had to order them, i will use them later on a bigger bar. i think im going to open up the hole in the fitting to the same size as the oil feed line, change out the push on brass barb to a compression fitting, then i will get more flow.   

Hilltop366

Is the motor loaded down a lot before the clutch slips?

I am running about the same size clutch and have more power with no clutch slipping issues .

I just thought of one thing to check, the lawn tractor that the motor and clutch came from came with a feeler gauge to put in the clutch in three different places next to the spring adjustment bolts and adjust the gap on the clutch, I would have to check for the size of the gauge but 20 thou comes to mind.

The first chains I had were skip tooth and had not been reground, they cut very rough until I reground them 10°. There must have been a lot of sideways force on the bar grove and chain to make as much wave in the cut that it was doing. Eventually I started grinding them at 0° so I did not have to reset the grinder angle when switching sides.

shelbycharger400

kohler air gap spec middle is 16 thous.   i had it set to that, and tried everything all the way down to about 2 thousandths..  not much difference.  i can tell when their is a load, but it didnt load up the motor that bad, not any more than normal load when movin the yard .  chain is a full chisel   3623 005 0114.  seems the cutter is 1 1/2 in apart, i wasnt shure if that was going to load it up that much.

Hilltop366

This is what the rip chain that I received looks like, If you look close you might see that they didn't cut off the entire tooth, not sure if there is any advantage to this over taking the tooth right off, the other rip chain from baileys that I have is a full chain @ 10° out of the box. With the chain style like in the picture I would rarely slip the belt and with the full chain it will slip quite often. looking around on here I see some talk about horse power vs number of teeth when talking about circle saws I suspect the same holds true for saw chain.

As far as the clutch slipping goes if the clutch is working properly the load must be too much, kind of like a car with a worn clutch, if you are going up a hill in 5th gear and the clutch starts to slip you can put it in a lower gear and stop it from slipping or go up a less steep hill.



 

shelbycharger400

i picked up a full skip tooth chain from  a local saw shop few hours ago, still a chisel tooth.  If i have time tomorrow, ill try to throw it on and give a run fri or sat.  im starting to think with the overload idea,  with the speed being part of the problem.  Im looking into a mechanical tensioner, just so i can run the fast speed/ fast rip

fishingmike

One thing I noticed with my clutch was that if you over tighten the belt it would make the clutch slip. The problem then becomes the belt slipping. After much struggling with that smiley_furious3 I switched over to a solid pulley on the motor and one the jackshaft with a spring loaded tensioning pulley on the slack side of the belt. I would suggest trying to loosen your belt slightly and see if that helps, but I think you'll save yourself a lot of trouble in the long run to just switch over to solid pulleys and a spring loaded tensioner.
The chain I use is .404 x .063 full comp chisel with every other pair of cutters ground off. Remaining teeth are about 5° the rakers set at 50 thousandths. Cuts pretty smooth and fast. If I try to push ahead too fast the cut gets rough.

shelbycharger400

fishingmike, are you running with the belt tight all the time/ chain running all the time?
I drew up a plan for a release/tighten tensioner with a rod link, spring to hold it in release mode.  i think i will work on making that this weekend.

yea, i do have the belt on the tight side,  I threw on the skip tooth unmodified,  i did play around with a 12in dia firewood boxelder.   its oviously softer material, but i was able to travel a small amount faster than the oak trial.  I noticed the chain likes to bouce a smaller amount more if i push it more agressively, but i was constantly tensioning it, aparently the carlton chain wasnt prestreached or something . I did have some more issues with the clamps not holding, they are a work in progress too. clutch slipped when the log would move on me as well.   when the clamps held . given this is only a foot long log, vibrations are big,  the chain cut marks wernt too concerning, but more tho than the full comp. 

fishingmike

http://www.youtube.com/watch?v=L8bdo5qsBeA&feature=mfu_in_order&list=UL
Here is a short video of my slabber.
I would suggest using the spring to keep the tension on the idler that way it can flex a little with the belt when your cutting through knots.
As far as the log clamps go, it depends on if your planning on making dimensional lumber or just slabs.

shelbycharger400

do notied, ur mill is very similar to mine.  one thing i did notice, i didnt use any wedges when cutting my short pieces, im currious now if that has some play with binding up the chain in the cut, usually it did it to me after about 6 to 9 inches into the log that was 18 inches long, i noticed the piece that was being cut vibrated more than the log did. also i never thought of using the  perforated angle when i built my mill, i was planning on using 80/20 on the nice one when i figure out the issues ect with this one.  that perf'd angle is cheaper, and a buddy can make me milled angles with all the specked out holes for the bolts to go.

My plans are making some lumber with the mill, i want to redo the kitchen for the wife, I didnt get much done today, but I did rework the dogs today a bit,, they work ok, i havent cut into the log with them,  i have to put a 4inch block under the log to get the height up, due to my inherant design flaw where my bar sits now, bar is 6 inches up from the deck, it sorda came about when i reworked where the wheels go, and made them all 4 adjustable for height, and went with larger wheels that had bearings vrs the bushing ones before.  I wish i would have put the wheels/ angle iron on the outside of the track instead of ontop of it. im going to make different log bunks, and clamps, the ones i have are too cumbersome,   i have come across a video of some nice design, im going to try to make them.  I will get a camera and photo the ones now, the idea might work for someone. 
Thing i do like about this forum, is all the help people are willing to give, and the information that one will post on what works, and what dosn't work.
this is what im thinking now... on clamps/bunks.
i came across this video
http://www.youtube.com/watch?v=geQold6y2qI

Hilltop366

I like simple look and design of the mill in those videos. The second one reminds me of the jonsered csm. I think it could use more bunks closer together so things don't sag when the log starts to get thin, they look kind of far apart to me.

There is a lot of extra sideways force on the log and mill compared to a band mill it seems to take some extra care to make sure things don't move.

I used a sharpened 1/4" bolt near the top of my back stop to help prevent things from slipping it sticks out about 1/4". The dogs I made are threaded with a point in the middle a simple cam lock would be a lot faster. I may get some pictures later.

shelbycharger400








the photo uploader prog . is a bit different now.. kinda like 2 prog running, 2 different ways now to post a picture/upload a pic. , neither is workin right for me , must be me doing something wrong.
the pictures are from the mill up by the garage, its easier to work on it their.
the clamps, the backstops i stuck in their yesterday, i was measuring the long bars, seeing what works best, i have yet to cut them off.    i have 2 sets of these.  all crossmembers are 1 ft on center.  3 are hard welded in, so the distance betwen the welded 2x2 square's are 3 ft on center.   it has come out very well that the ones i have been working on are removable.   the threaded rod clamps, work ok, the tubes are 8 inces long,  the t's on them are too small, they need to be bigger , i use a wrench on them to tighten to the logs.  I chose my layout baised upon wanting to do very short logs, it is way easier to cut in one or 2 ft long sections and toss them on, what im finding is its very hard to clamp them.   i come across a lot of high figured material,and odd ball stuff from urban trees that is dumped off at the compost site, last summer their was logs 3 ft dia, at only 2 ft long their, willow, but none the less.   i have some of said outback that the wood is bright orange that darkens to blood red.


Hilltop366

Backstop with sharpened bolt to help hold log. The pin sticks in the log 1/4" it has to be quite sharp and not to long so it does not hold a cant off and make it out of square, I can also turn the stop 1/4 turn if I want a flat surface.


 


Log clamp. It is kind of slow and awkward but holds quite well, because the whole clamp turns in the frame it is not necessary to change the height every time, it will lower and raise quite a bit just by turning it.


 


The other end of the log clamp.


 


The log clamps I made are removable so I can cut different length logs, I found that the would not go far enough apart with longer logs and the ends would shake so i added some log dogs to each end.

Because I cut towards the clamp it puts pressure down on the out side of the clamp, if I was to cut the other way it would need a pin across the top of the pipe (bottom photo) because it would be pushing up

shelbycharger400

tossed on a  6 ft long ash? log 8 to 10 in dia.  i found at the compost side,
figured id give it a whirl with an unfrozen log.
havent had time to work on the mill much,  so i took off the welded washers on the bolts and used a cresent wrench and tightend down the bolts on the log.

i took off a 2 inch thick slab for first cut.. wayy slow. I didnt slip the clutch anymore,  i had the belt too tight and also it was bottomed in the clutch pulley before.    the skip tooth chain on this log turned out rather smooth except where i bound up from tryin to move too fast.  Im thinking my rpms are too slow...  wrong belt on it currently so chain is only running 6000 rpm.   If i get the right belt  im hoping to be up to 7200 rpm.
also i switched over to veg oiler, having issues with oiler.    still have issues.  A 3/32?  inside hole on 1/8 in line  isnt delivering enough lube.  i only have 6 inches of 1/8 line coupled to 1/4 inch line. looks like im going to have to redrill the bar and install my 1/4 pushloc fittings.  and add a second oiler.

next up is orderin up a loop of 114? count  ripping chain.

wondering if my 630 johnsreds will handle a 36 in full comp and a 36 in skip tooth chain.   compression on this beast is not a problem.  i have to start it with my foot in the handle,  one hand on the front handle, other on the pull rope


  

 

Thank You Sponsors!