Chainsaw Repair

Chain - Grinders - Filing - Wood Milling - Tools - Welding - Machinist - Mowers - Tillers => Chain - Bars - Grinders - Filing => Topic started by: Philbert on August 14, 2015, 02:54:51 pm

Title: Depth Gauge Rounding and Drive Link Deburring Wheels
Post by: Philbert on August 14, 2015, 02:54:51 pm
Chain manufacturers recommend rounding over the depth gauge on each cutter, to match the original factory profile, after adjusting their height.  The sharp point left where the flat, filed area meets the rounded portion can dig in and lift the cutter when it rotates in the cut.

A lot of guys just don't do this. Those that do, often use the same file that they used to file the depth gauge.  Some use a bench grinder. Some use a Dremel tool.

Similarly, when a chain jumps out of the guide bar groove, burrs are formed on the drive links where the sprocket keeps hitting them.  These burrs can keep the drive links from fitting back into the groove, and must be removed. Some guys file these off.  Some guys use a bench grinder.  Some use a Dremel. Some guys flatten the burrs with a ball-peen hammer on an improvised anvil.

For many years I used a large, 'Scotch-Brite' brand deburring wheel for both of these tasks.  It works fast, and leaves a smooth, polished finish.  The wheels I used were 6 or 8 inches in diameter; 1/2 to 1 inches thick; mounted on a bench grinder or motor shaft; and about the consistency of hard, dense felt.

One problem was that the sharp depth gauge and drive link corners would just 'eat' these somewhat expensive wheels (typically $40 - $60).  While they would last 'forever' when cleaning rust off garage sale finds, etc., the chains made quick work of them.

The other challenge was polishing these fairly small parts without hitting my newly sharpened cutter edges, hitting the tie straps, or unintentionally re-shaping the drive link profile.  I decided to try a new approach.

Philbert
Title: Smaller Wheels - Different Types
Post by: Philbert on August 14, 2015, 02:57:00 pm
Companies like 3M, Norton, etc., make a wide range of abrasive products, with many variations, to meet many task requirements.  While this is great for meeting the customer's needs, it can be overwhelming to identify the 'best' product for a specific application.

With the help of a 3M technical representative, I'm now trying some smaller, similar-but-different products for depth gauge rounding and drive link deburring, and promised to share the results with others, to make it simpler for them.

I am starting with smaller diameter, thinner wheels, which will 'fit' better into these chain locations. These are mostly 3-inch diameter by 1/4-inch thick wheels, that fit onto 1/4-inch or 3/8-inch mandrels.  Of course, other sizes (2-inch diameter, 1/8-inch thick, etc.) will also work, but these appear to be more commonly available, and to be a better cost/value/size choice.

Each is described as a 'unitized wheel'; essentially a compressed ScotchBrite-like product that can be rotated in either direction - *not all can*.  In addition to size and mounting type, they vary in a few ways:

- Density / Hardness: Designated by number (2 - 11), a softer wheel (lower number) will conform easier to a contoured surface than a harder wheel (higher number), which will last longer.

- Mineral / Abrasive type: 'A' aluminum oxide, 'S' silicon carbide, 'C' ceramic.

- Grade / Coarseness: Might be specified by grit size (like sandpaper), or in qualitative terms ('VF' very fine, 'F' fine, 'M' medium, 'C' coarse, 'XC' extra coarse, etc.).

This means LOTS of combinations and choices!

http://www.use-enco.com/CGI/INPDFF?PMPAGE=261&PMCTLG=00

https://www.mscdirect.com (select 'Virtual Big Book', enter page 1043)

Philbert
Title: Line Up for Testing
Post by: Philbert on August 14, 2015, 02:58:24 pm
The photos show the 5 different wheels I am going to try, along with 5 different arbors! 

From left to right (density, mineral, grade): 9-C-XCoarse; 9-C-Coarse; 5-A- Fine; 6-C-Medium; 2-S-Fine. The other markings are 3M marketing/application terms.

These discs have either 1/4-inch or 3/8-inch ID mounting holes, and I have them mounted on 1/4-diameter arbors which can fit into: a drill press; hand-held drill; die grinder; drill chuck on a bench motor (my choice). Some are also available with a 'Rol-Loc' mount, in larger diameters for use on a bench grinder, etc.

These particular discs are speed rated from16,000 to 18,000 RPM, and need to be used on speed-compatible arbors and tools - check what you have/use.

They are commonly used for weld blending, and are sold through industrial suppliers (Grainger, Fastenal, Enco, MSC Direct, etc.), as well as welding supply houses and Internet vendors.  Cost seems to run between about $5 - $12 each wheel (without the arbor), depending on the size, type, vendor, and quantity: some need to be ordered in boxes of 40 to get the best price, so maybe find some friends to split a box, or be nice to a welder.

Philbert
Title: Re: Depth Gauge Rounding and Drive Link Deburring Tools
Post by: Cut4fun . on August 14, 2015, 02:59:28 pm
Good thread and Thanks for time doing so.
Title: Re: Depth Gauge Rounding and Drive Link Deburring Tools
Post by: srcarr52 on August 14, 2015, 05:07:35 pm
I use a 2" angle grinder with a sanding wheel (120 grit) to deburr drive link. I used to use an air grinder but now I have a 2" grinder that fits on my foredom cable drive so I can control the speed with a foot pedal.
Title: Re: Depth Gauge Rounding and Drive Link Deburring Tools
Post by: Philbert on August 14, 2015, 05:48:20 pm
I use a 2" angle grinder with a sanding wheel (120 grit) to deburr drive link.

That sounds like a good idea too!  You are using the flat face of a sanding disc, versus me using the edge of a wheel, correct?  I have a right angle attachment for my Dremel tool that I could try. For some reason I only thought of, and seen, using the Dremel stones  for doing this.

Do you also use these discs to round the depth gauges?

Thanks.

Philbert
Title: Re: Depth Gauge Rounding and Drive Link Deburring Tools
Post by: 3000 FPS on August 14, 2015, 07:52:18 pm
I use a small air grinder with a fine 2" disc sander or file for deburring drive links.

For the depth gauge I have a Tecomec chain grinder that I use and dedicated to only doing the rakers.   I then took one of the wheels and shaped it to the raker and found it to give the rounded shape that I want and consistent height from raker to raker.   I  was using a dremel with a chain vise that I made but found the Tecomec to be faster and more accurate.   

I still use the dremel sometimes to thin the top part of the raker.
Title: Re: Depth Gauge Rounding and Drive Link Deburring Tools
Post by: Old Iron Logging on August 16, 2015, 02:44:10 pm
When we threw a chain at work, we just put it back on bar with about an inch of slack. Start saw and blip the throttle a couple of times. Burrs gone. No harm to bar or chain. If you try this method keep the chain tight enough not to bump the chain catcher.
Title: Re: Depth Gauge Rounding and Drive Link Deburring Tools
Post by: HolmenTree on August 17, 2015, 08:29:33 am
Yup that's all I ever do too. Last time I used a file or a stone on a peened drive link was over 30 years ago when I threw the 5 ft chain on my 090 with its original spur sprocket drum. :D
Rounding off the leading edge of the depth gauge I use the same flat file that I lower them with. Then after a few hours of cutting in wood they get perfectly honed smooth with the perfect angle of approach matched to its cutter bit size.
Title: Re: Depth Gauge Rounding and Drive Link Deburring Tools
Post by: Philbert on August 22, 2015, 08:21:55 pm
Depth Gauge Rounding Test

Totally subjective, but systematic, testing of the 'unitized' blending / deburring / polishing wheels described above.

Test Parameters: Primary test subject was a STIHL 3/8, .050, 84 DL chain with bumper drive links. I had to lower the depth gauges quite a bit on this chain, so a lot of reshaping was needed on the depth gauges and low-kickback bumpers to round off the flat tops created by my 511A grinder. Lots of links to test.

Secondary test subjects were about 8, STIHL .325,  .063, 67 DL chains with either drive link bumpers or tie strap bumpers. These required mostly light rounding.

Wheel arbors were mounted in a drill chuck on 2 bench motors: 3450 and 1725 RPM.

Results? 

Wheel Size: I really like the 3-inch diameter, 1/4-inch thick wheels for this task.  I had been using much larger format (6 and 8 inch diameter, and 1 inch thick), 'convolute' (softer, directional) wheels, because those were what I had.  These smaller wheels minimize the chance of hitting the freshly sharpened cutting edges, and easily reach any burrs on the drive links (not tried in this test).

Wheel Grade: Predictably, the coarser wheels removed material faster, but left a deeply scratched finish. The finer wheels removed material slower, but left a highly polished finish. 'Medium' to 'Medium +' seemed to be the best compromise for this purpose.

Wheel Density: Wheels in the '6' to '8' range seemed to work well shaping the depth gauges and bumpers with a minimum of wheel wear.

Abrasive Type: I didn't get to compare identical aluminum oxide ('A') and ceramic ('C') wheels side-by-side.

Speed: The 3450 RPM motor worked much better than the 1725 motor.  In addition to the higher speed of removal, the coarser wheels really chattered at the lower speed.  If using a slower motor, go with a finer abrasive grade.

Summary:  All of these wheels worked.  If you were given a box of any of them for free, I would not throw it out.  But if you are buying them, you might as well get the ones that work best.  I would choose 3 x 1/4 inch 'unitized' wheels with markings like:

6-A-Med, 6-C-Med+, 7-A-Med, 8-A-Med (availability will vary with manufacturer)

Philbert
Title: Re: Depth Gauge Rounding and Drive Link Deburring Tools
Post by: Philbert on August 22, 2015, 08:31:39 pm
Some Other Notes

- As noted, the faster wheel speed worked better.  Some of these wheels are rated up to 18,000 RPM, which is 5X the maximum speed I tried.  A die grinder mounted to a bench might be an interesting way to try these higher speeds.

- I would also want to test the coarser wheels at the higher speeds to see if I could get fast material removal with less deep scratching.

- One, 2-inch diameter wheel was tried.  It worked, but was not as convenient, or as fast, as the 3-inch wheels.

- I also tried one, 6-inch diameter by 1/2-inch wide, soft, fine wheel on the slower motor.  The faster edge speed helped, but did not make up for the slow cutting speed.  The wheel was still too thick, and the larger diameter restricted positioning of the cutters more than the 3-inch wheels.

- Thicker wheels might work with chains that do not have the reduced-kickback bumpers, due to more clearance between chain components.  I wanted something that would work with all chains.

- 1/8-inch wide wheels would also work, but the price difference is minimal, compared to the 1/4-inch wheels, which have twice as much abrasive material.

- It is still possible to nick your newly sharpened cutting edges if you are not careful, but you can also do this with a file, Dremel, etc.

- All of these test subjects were reduced-kickback style chains.  Regardless of whether they had bumper drive links or bumper tie straps, the bumpers were harder to round, and took more time to round, than the depth gauges(!).  It took 1 to 1.5 seconds to round each depth gauge.  Bumpers took about 3 seconds each.

- Shaping the rounded profile of the depth gauges was easiest to control with the flat depth gauges held perpendicular to the wheel edge.  Holding the depth gauges parallel with the wheels produced a smoother finish, even with the coarser wheels, but increased the risk of contact with the sharpened cutting edges.

- As the wheel wore and formed a concave edge, I periodically flipped the chain (polished from the other side) to keep wheel wear even.

- Remember that these wheels remove metal fast! Spend too much time focusing on the smooth curve and you might remove several thousandths more than you intended, ending up with a more aggressive chain!

Philbert
Title: Re: Depth Gauge Rounding and Drive Link Deburring Tools
Post by: HolmenTree on August 23, 2015, 09:21:33 am
Rounding off the leading edge of the depth gauge I use the same flat file that I lower them with. Then after a few hours of cutting in wood they get perfectly honed smooth with the perfect angle of approach matched to its cutter bit size.
How well a chain cuts is dependent not only at the cutting edge but also at the surface of the depth gauge.
As I explained how the leading edge of the depth gauge in the wood kerf gets worn smooth after  a few hours of steady cutting . The surface of that leading edge is perfectly matched to the angle of the cutter with the least amount of friction due to its  best method of honing.
Your good to go for quite a few more touch ups of the cutter with the round file before the DG has to be lowered again.
Title: Re: Depth Gauge Rounding and Drive Link Deburring Tools
Post by: Philbert on August 24, 2015, 04:08:02 pm
- As noted, the faster wheel speed worked better.  Some of these wheels are rated up to 18,000 RPM, which is 5X the maximum speed I tried.  A die grinder mounted to a bench might be an interesting way to try these higher speeds.

- I would also want to test the coarser wheels at the higher speeds to see if I could get fast material removal with less deep scratching.

3M guy confirmed that wheel performance would improve with the faster speed, and that they would act like a finer grit at those 18,000 RM speeds.  Said that they would also last longer at higher speeds.

Philbert

P.S. - my neighbor suggested that I try a Harbor Freight die grinder 'for about $20'.  Got me excited.  But they are more like $50.  And I need variable speed to limit it to 18,000 RPM. . . . will keep an eye out at garage sales.
Title: Re: Depth Gauge Rounding and Drive Link Deburring Tools
Post by: HolmenTree on August 28, 2015, 12:06:04 am
The day I use a grinder on my depth gauges is the day I'll  pack 'er in ;D :-*
Title: Re: Depth Gauge Rounding and Drive Link Deburring Tools
Post by: Philbert on August 28, 2015, 04:02:09 pm
The day I use a grinder on my depth gauges is the day I'll  pack 'er in
I've seen a lot of guys post on A.S. that only file their cutters, but are happy to grind their depth gauges.  Took me a while to grind them without burning, especially on low-kickback chain with the extra bumpers.  Now it goes fast.

Philbert
Title: Re: Depth Gauge Rounding and Drive Link Deburring Tools
Post by: Al Smith on August 29, 2015, 07:11:09 pm
I just use a flat file when I file the rakers which might be two or three times in the entire life of the chain.

Some people make love to a work chain like it's rocket science which it isn't .A race chain however is one to take the time with IMO .

The way I look at a work chain is if it's throwing  big old chips I just leave it alone .I could care less if every tooth is the same length and all the stuff the so called experts say .
Title: Re: Depth Gauge Rounding and Drive Link Deburring Tools
Post by: jmester on August 29, 2015, 08:55:52 pm
Al, could not agree more.
Title: Re: Depth Gauge Rounding and Drive Link Deburring Wheels
Post by: Cut4fun . on August 30, 2015, 04:33:55 pm
Fixed?
Title: Re: Depth Gauge Rounding and Drive Link Deburring Wheels
Post by: 3000 FPS on August 30, 2015, 10:18:15 pm
I don't have to cut wood for a living and it is really a hobby for me.   Since part of the enjoyment is finding out all the technical aspects of the hobby, I like fussing over a chain and learning all I can to make it cut straight and fast.   Heck if did not like it why spend a good chunk of change on a square grinder.   Not only I did I enjoy learning how to use it but I really liked the results too.  So we all come at this with alittle different perspective.
Title: Re: Depth Gauge Rounding and Drive Link Deburring Wheels
Post by: Philbert on August 30, 2015, 11:20:21 pm
Fixed?
Thanks!

(I asked to change the thread name slightly to reflect the wheels I was using, as opposed to other tools or methods).

. . . I like fussing over a chain and learning all I can to make it cut straight and fast.

I think that the chain is the most important part of a chainsaw.  That said, everyone needs to find what works for them, how much effort they want to put into it, etc.


Philbert
Title: Re: Depth Gauge Rounding and Drive Link Deburring Wheels
Post by: Philbert on September 02, 2015, 10:54:48 pm
Here's another way to deburr drive links!

Philbert
Title: Re: Depth Gauge Rounding and Drive Link Deburring Wheels
Post by: HolmenTree on September 03, 2015, 10:26:07 pm
 Philbert that's a pretty neat little grinder. Stens has been around for decades,  good to see them still in the chainsaw biz
But $635 US you gotta deburr a lot of DL'S to make it pay.
BITD when I built my race chains I polished the depth gauges and cutters with slips starting with a oil stone then finishing with a Japanese  Gold water stone slip.
Things a person would do :D
Title: Re: Depth Gauge Rounding and Drive Link Deburring Wheels
Post by: Philbert on September 03, 2015, 11:36:58 pm
Philbert that's a pretty neat little grinder.

It's an accessory for the $20,000 Franzen automatic grinder:
http://www.franzen-maschinen.de/45.0.html?&L=1
https://www.youtube.com/watch?v=1fRlAiDU5Ek
https://www.youtube.com/watch?v=wxcb7DpcDD4

(Fish said it's all about the set up: if you are running lots of identical chains, it can make sense in labor savings in a busy shop.  Otherwise, it is a great way to attract attention.)

Philbert
Title: Re: Depth Gauge Rounding and Drive Link Deburring Wheels
Post by: Philbert on September 04, 2015, 12:38:52 am
Love to find one of these at a garage sale:

http://www.madsens1.com/sil_hdg6.htm

http://www.silveychaingrinder.com/round-depth-gauge/hdg6-depth-gauge-grinder

Philbert
Title: Re: Depth Gauge Rounding and Drive Link Deburring Wheels
Post by: Cut4fun . on September 04, 2015, 12:42:20 pm
Knew a guy that had one in his shop local. OK for work chains.  He sold it later on.