Norwood HD36 blade guides - problem removing Allen screws

TmbrWlkr · March 26, 2021, 10:20:42 PM

I have a Norwood HD36 - with ceramic blade guides. The aluminum block that holds the ceramics has steel Allen screws tensioning them in. I attempted to remove them to change the blade guides with the result of stripping 2, snapping an Allen wrench socket off, then drilling for an easy out which I subsequently snapped. During all this drilling, stripping, and snapping I was alternately heating and cooling the block while applying penetrating oil. End result I ordered a new block from Norwood.

Is there some kind of chemical/metallurgical reaction between steel and aluminum? The Norwood tech recommended I coat the screws in silicone.

Anyone else have this problem?

Southside · March 26, 2021, 10:32:19 PM

I would coat them with a never seize product before installing them, I use it on just about everything. Properly torqued they will not back out on their own.

Patrick NC · March 27, 2021, 07:20:24 AM

X2 on using an anti-seize on them. I eliminated the problem altogether by installing roller guides. I highly recommend them.

thecfarm · March 27, 2021, 08:09:26 AM

Quote from: TmbrWlkr on March 26, 2021, 10:20:42 PM
Is there some kind of chemical/metallurgical reaction between steel and aluminum?

I have thought the same thing. My neighbor had a corvette of some year, and he complained about that.

petefrom bearswamp · March 27, 2021, 08:15:46 AM

Wrecked some aluminum storm windows in the manner you describe many years ago.
I think I read something about this somewhere

moodnacreek · March 27, 2021, 08:43:09 AM

Unless it needs locktite it gets neversieze around here.

TmbrWlkr · March 27, 2021, 08:45:42 AM

Quote from: Patrick NC on March 27, 2021, 07:20:24 AM
X2 on using an anti-seize on them. I eliminated the problem altogether by installing roller guides. I highly recommend them.

Tell me more about them. Where are they available for the HD36? Installation difficulties, maintenance? Accuracy? Cost? Pics? Any info would be appreciated.

Gere Flewelling · March 27, 2021, 08:53:21 AM

I have had some interesting problems with steel bolts in aluminum over the years. I have observed that though anti-seize is good stuff on steel, it doesn't seem to work as well on well on aluminum. Where I work, we have snow cats that have rubber belts attached to steel cleats with steel bolts. During operation the bolts attaching the belts to the cleats will snap off at the top of the threaded area on the cleat. The bolts are originally secured with red (high strength) lock-tight. I have found that the only way to get the broken bolt out is to drill and use a tapered square easy-out in the bolt. Then just apply loosening tension with an adjustable wrench while warming the aluminum thread area with a oxy-acetylene torch. I hold the torch further away from the aluminum, compared to what you would do with steel. Keeping the heat moving over a larger area, it will start warming up and the tension you feel on the adjustable wrench will all of a sudden release when the lock-tight releases. You can then screw the broken stud out. I think you will find that if you use the lock-tight liquid on the new screws, it will seal out corrosion and then release when warmed. I might suggest the blue medium strength lock-tight for your application. I think you will find that the next time you need to loosen the set screws, you will have better luck knowing what you need to do when loosening lock-tighted screws. The heat may work on corroded screws as well. I just have not had that experience.

Patrick NC · March 27, 2021, 09:17:55 AM

Quote from: TmbrWlkr on March 27, 2021, 08:45:42 AM
Quote from: Patrick NC on March 27, 2021, 07:20:24 AM
X2 on using an anti-seize on them. I eliminated the problem altogether by installing roller guides. I highly recommend them.
Tell me more about them. Where are they available for the HD36? Installation difficulties, maintenance? Accuracy? Cost? Pics? Any info would be appreciated.

Norwood has a kit to upfit to Norwood rollers. IIRC it was about $300. It requires a little shimming to get the blade deflection correct, but it's a pretty easy installation. The kit comes with replacement shafts that the rollers go on that go right in the same place that your ceramics attach. No fabrication. Just a little shimming with some washers. Norwood won't tell you about them unless you ask because they try to promote the ceramics as being better. ( Not the case for me. ) I drank the ceramic Kool aid for awhile both with this mill and my last one, but have been fully convinced that the rollers are superior . Straighter cuts, faster feed, and longer blade life. I will get some pictures of them later today and post them. Call Norwood sales and tell them what you want and they will send them. Send me a PM if you get them and I'll walk you through the shimming process.

TmbrWlkr · March 27, 2021, 09:28:38 AM

Patrick NC - thanks loads - looking forward to your pics. I am on vacation right now but when I get back (10 days or so) I will call Norwood and get current pricing and availability.

Patrick NC · March 28, 2021, 11:41:09 AM

Here's some pictures of the Norwood roller guides. Like I said, it takes a little shimming to get it right, but it's not difficult. Norwood will tell you to shim to 1/8" deflection. I found that wasn't quite enough so I went to 1/4". Each side is different. The fixed side gets shimmed 1/8" and the movable guide gets 1/4". I just put spacers (washers) where the guide brackets bolt to the head.
You do have to make a new mount for the blade lube hose. I just used a bolt and plastic elbow to allow the hose to drip behind the guide onto the blade.

TmbrWlkr · March 28, 2021, 03:37:44 PM

Do you have build up issues on the blade?

jpassardi · March 28, 2021, 06:09:57 PM

Aluminum and steel or other dissimilar metals in contact can cause galvanic corrosion when in contact with an electrolyte (in this case blade lube water). It has to do with the normal electric charge of different metals.
I would suggest anti-seize also, I try to use it on most bolts on the mill. Roller guides as suggested would be ideal.

Patrick NC · March 28, 2021, 07:55:01 PM

Quote from: TmbrWlkr on March 28, 2021, 03:37:44 PM
Do you have build up issues on the blade?

Not any more than I had with the ceramic guides. If pitch starts building I usually just turn the lube up and it usually fixes it. Actually I think I had more problems with build up when I had the ceramic guides.

TmbrWlkr · March 31, 2021, 04:58:26 PM

Thanks for all the advice and insight guys. Unfortunately I have a new block (probably waiting for me at home) from Norwood, and the ceramic guides I was going to install. I have a bunch of red pine and locust to cut sitting by the mill. I think I am probably going to give the ceramics another chance, and if they continue to frustrate switch to rollers.

Wish me luck.

Patrick NC · March 31, 2021, 06:37:34 PM

When using the ceramic guides make sure you use max blade tension and clean your bandwheels often. Pay special attention to the grooved the belts ride in. Ceramic guides are designed to not touch the blade so if you get a little vibration from build up, it transfers directly to the blade and causes flutter. That can cause the ceramics to get knocked out of adjustment. I chased that problem for a while and ultimately was the biggest reason I switched to rollers.