# How much resistance should there be after back lapping



## kur1j (Jul 2, 2017)

I just replaced the bearings, reel, and bedknife on my JD 220c. I just got it all back together and back-lapped it.

One thing I was never able to figure out is how much resistance there should be when spinning the reel. It's cutting the paper really well but not sure if there is too much resistance in the spinning of the reel?

Does this look normal?

https://youtu.be/TS9zKmfh1Hw


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## ABC123 (Jul 14, 2017)

As long as it doesn't make an audible squeal of metal on metal. You can also do the two paper test and cut one and bend the other.


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## kur1j (Jul 2, 2017)

The only slushing, chinging noise thst a reel makes. No screeching thst I can tell.


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## ABC123 (Jul 14, 2017)

Should be good to go then.


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## SCGrassMan (Dec 17, 2017)

I was advised to keep a 0.002" gap (no contact) on mine for durability. Mines a toro gm1600 and I have Zeon Zoysia. Your mileage may vary.


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## Ware (Jan 28, 2017)

SCGrassMan said:


> I was advised to keep a 0.002" gap (no contact) on mine for durability. Mines a toro gm1600 and I have Zeon Zoysia. Your mileage may vary.


Light contact, no contact, spin only, spin-relief... it's one of those things where if you ask 4 different reel mechanics you're likely to get 4 different answers.

FWIW, the Toro service manual just says:



> After the adjustment is accomplished, check to see if the reel can pinch a strip of paper when inserted from the front and cut the paper when inserted at a right angle to the bedknife.


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## g-man (Jun 15, 2017)

This is for the QA5 head but I don't see why it doesn't apply (0.002in (0.05mm)of clearance).


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## Greendoc (Mar 24, 2018)

Using the 180 grit, I backlap without tightening the reel further until the reel has just a trace of contact. I do not believe in zero contact. Toro explained why in their "Reel Mower Basics" bulletin.


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## Ware (Jan 28, 2017)

Toro Reel Mower Basics

I had this bookmarked. Linking it to save someone a search. :thumbup:


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## SCGrassMan (Dec 17, 2017)

Yeah pinching paper would probably be around 0.002".

And agreed Ware, 4 guys would probably give at least 5 answers though 

I imagine the grind (spin Vs relief) and type of grass etc makes a difference.

But I can tell you at 0.002" mine is cutting great and it's quiet!


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## Greendoc (Mar 24, 2018)

Here is the study that quantifies what happens when a reel is maintained with the zero contact no relief method of mower set up. I saw the shredded leaf tips and the exploded drive chains or cut belts long before reading this. The work was confirmation that I was not out of line or pursuing an agenda. Other than the agenda of non shredded leaf tips. Zoysia shreds something awful when a zero contact mower is put on it. https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=2031&context=farms_reports


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## kur1j (Jul 2, 2017)

Greendoc said:


> Here is the study that quantifies what happens when a reel is maintained with the zero contact no relief method of mower set up. I saw the shredded leaf tips and the exploded drive chains or cut belts long before reading this. The work was confirmation that I was not out of line or pursuing an agenda. Other than the agenda of non shredded leaf tips. Zoysia shreds something awful when a zero contact mower is put on it. https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=2031&context=farms_reports


So would that mean that you couldn't fit a .001 feeler gauge between the bedknife and reel? It's hard for me to quantify "light can't contact".

I just don't want to have to spend 250$ replacing the reel if i ruin it.


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## Greendoc (Mar 24, 2018)

0.01" would not fit. 0.0001" might. i simply backlap until the reel turns very smoothly and does not sound like it is grinding hard.


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## SCGrassMan (Dec 17, 2017)

@kur1j

https://smile.amazon.com/dp/B0752XD2YZ/ref=cm_sw_r_cp_awdb_t1_2x4YAbN607PWK

Quantify away  or, a single sheet of paper dragging between the two with some resistance.


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## kur1j (Jul 2, 2017)

@SCGrassMan

So I already have feeler gauges but the problem for me is that if I set it at .002 across the bedknife it won't cut paper. When it's at .001 it will cut paper but seems more than "light contact".

Maybe I'm doing the whole procedure wrong.


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## SCGrassMan (Dec 17, 2017)

If you're using a 0.001 and there is contact you're doing it wrong. The feeler gauges are to ensure that there is NOT contact.

When using a 0.002 feeler, when you slide it between the reel and the bedknife it should drag a little. You don't want it to ether get stuck, or completely pass through without touching.

Does that make sense?


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## kur1j (Jul 2, 2017)

@SCGrassMan

Hmmm. Well I was going for the "light contact" that greendoc suggested.

So maybe my basics are all messed up for this whole procedure. Here is what I've been doing.

Set to .001 (or .002) with feeler garage all the way across. To me this where the .002 for example will get resistance when sliding between the contact point of the reel blade and the bedknife. At that point will backlap it. Using 120 and then 220 grit compound. If i do this at .002. The reel will not cut paper. It will bend the paper over, but won't cut it. .001 it will cut "mostly". Sometimes it will cut sometimes it will bend the paper over. But I can certainly hear the bedknife and reel making contact at .001. Maybe I'm not ************ it long enough?

What should my whole procedure be?


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## Greendoc (Mar 24, 2018)

If a little bit of backlapping does not allow the reel to cut paper with that kind of clearance, then it needs to be spin ground and the relief angle re established. Carefully feel the cutting edge. Do not draw your finger along the length of the blade. Feel it at a perpendicular to the blade. If that edge feels rounded or not sharp. you need spin grinding and a relief grind.


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## SCGrassMan (Dec 17, 2017)

I'd defer to Greendoc. I don't do contact on mine because somebody much smarter than me told me not to lol.

But I'd agree with him on checking the sharpness etc. and possibly getting it reground. Could be the bedknife too.


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## Greendoc (Mar 24, 2018)

One more thing. If your bedknife has a similarly rounded cutting edge, it will not cut paper either. Facing the bedknife can work. I have seen bedknives come brand new with not so sharp edges. They get faced before mounting the bedbar on to the mower. I just re read your initial post. It can take some time backlapping with the 180 grit compound if you are trying to mate a reel and bedknife after installing for the first time.


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## kur1j (Jul 2, 2017)

Both the reel and bedknife are brand new out of the box (both). The reel is very sharp, not razor sharp but sure as hell sharp enough to cut you if you run your finger down the edge of it. The bed knife I wouldn't call "sharp" but it's as if a cnc cut a an edge on metal. Certainly not rounded off from what i can tell.

https://youtu.be/RDhbOlPQg5c

Around 8 min mark is when he's backlapping.

That's someone doing a backlap of a jacob.

It's adjusting the reel to bedknife while he's backlapping. Probably not the safest thing to do but not the point. It sounds like no matter what, there is "light contact".

I think I'm going to try it again, but do the backlap longer. I'm going to adjust it to as close to .001 or so the best I can, then backlap for 3-5min. At that point try to cut paper. If it doesn't, does that mean I need to backlap more or does that mean my adjustment was no good?


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## Greendoc (Mar 24, 2018)

I adjust for light to medium contact before starting to backlap. My clearance is obtained by lapping the reel and bedknife, together. If your reel can be moved by pushing on it with your finger, you are not too tight. If you need to grab it and it feels seized, it is too tight.


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## Greendoc (Mar 24, 2018)

I adjust for light to medium contact before starting to backlap. My clearance is obtained by lapping the reel and bedknife, together. If your reel can be moved by pushing on it with your finger, you are not too tight. If you need to grab it and it feels seized, it is too tight. Just watched the video of the Jacobsen backlap. That sound is of moderate contact even after backlapping. If there is relief on the reel, that is not a problem for any reel mower. What is bad, is when reels are adjusted tighter and tighter trying to cut when they are dull. That will cause the reel to be grooved.


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## SCGrassMan (Dec 17, 2017)

Yeah for ************ you need actual contact.


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## kur1j (Jul 2, 2017)

Ok thanks again for the help. I'm going to give this another go.

On a slightly different note, generally how often do I need to check to do a backlap? How often should I need to do a reel sharpening? I've only got ~6k sqft i'm cutting.

This might be a stupid question but would I need to take the reel off of the mower to get someone to sharpen it?


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## wartee (Mar 27, 2018)

@kur1j I would recommend sharpening once a year after the first few cuts in the spring. Then you'll probably need lapping in June or July.

You can do the paper test if you are curious about when it needs attention. Or you'll begin to notice a sort of haze on the grass where the ends are chewed up and brown.


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## SCGrassMan (Dec 17, 2017)

The answer I got to that question was once a year with a 0.002" gap, once a week with contact.


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## MasterMech (Sep 24, 2017)

kur1j said:


> Ok thanks again for the help. I'm going to give this another go.
> 
> On a slightly different note, generally how often do I need to check to do a backlap? How often should I need to do a reel sharpening? I've only got ~6k sqft i'm cutting.
> 
> This might be a stupid question but would I need to take the reel off of the mower to get someone to sharpen it?


On a 220c, or any other fixed-head greensmower, they will want the whole mower to do the sharpening. You will want the bearings and rollers in tip top shape before getting it ground.


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## kur1j (Jul 2, 2017)

@SCGrassMan

Every week sharpening?!? Or backlapping?

@MasterMech

Oh that's good! Pain in the *** to take the reel off.

You have any suggestions on where to find someone to perform sharpening on the reel? I've called a couple of the larger mower shops and they don't do it. I know that there has to be someone around that does maintenance on reels because I see lawn care companies running reel mowers on commercial properties.


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## SCGrassMan (Dec 17, 2017)

Backlapping


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