Tape Project Forum

Tape Machines => Tape Project Machines => Topic started by: ironbut on June 18, 2009, 01:00:53 AM

Title: Otari fixed guides
Post by: ironbut on June 18, 2009, 01:00:53 AM
Shawn will be working on some Otaris over the next few days as well. We are finding that the later models have a really miserable epoxy holding the fixed guides together and we are working our way through various non destructive methods of getting the little b*****ds apart in order to modify them.

Have you tried soaking them in acetone or MEK? I'm thinking you probably have. Sometimes if that won't work alone, if you boil the parts in water for about an hour and then soak them in a solvent that works a little better. The boiling causes small cracks that the solvent can enter and do their thing (kind of a mild version of torching a bolt). There are a lot of 2 part adhesives though and finding out exactly what you're dealing with is key. I'd imagine that since they're guides, whatever they used is probably more alcohol/head cleaner resistant than most.

Maybe I should drive over to their new distributor tomorrow and "turn on the ole charm"! Even if they don't tell me what the bonding agent is or give me a handful of guides, they'll be begging to deal with you guys!
Title: Otari fixed guides
Post by: docb on June 18, 2009, 10:02:04 AM
We've tried acetone, which works on the older ones. There are some plastic edge guides in each guide - not sure what kind of plastic. It handles acetone OK, but we haven't ramped up to MEK yet. Heat seemed to help a little, but once again there is some concern about messing up the plastic so we haven't really cooked one yet. We only have a few spares that we can afford to destroy so we are being fairly methodical.
Title: Otari fixed guides
Post by: Ben on June 18, 2009, 10:40:44 AM
I has hoping just to upgrade the tension arms on my Otari 5050 II , but I can't get them off as the screw is too tight. Any ideas on that one. That is the only thing
I really plan to upgrade with doc's upcoming mods. Ben.
Title: Re: Otari fixed guides
Post by: Listens2tubes on September 10, 2011, 04:19:06 AM
The black guides are so hard the carbide cutter dulls just taking the finish off. With an attempt to cut into the guide is made it chips. Have you determined what this "plastic" is? What technique is working for you? I'd like to be a tester for the Otari kit.
Title: Re: Otari fixed guides
Post by: docb on September 10, 2011, 10:16:22 AM
Whatever the edge guide material is (ceramic? Bakelite?) it can take heat. Shawn uses a heat gun to loosen the thread locker on the head block guides. Not sure if he has had issues with the screws on the tension arms. I'll let him add any tips he may have.
Title: Re: Otari fixed guides
Post by: Listens2tubes on September 10, 2011, 05:40:25 PM
Actually why remove the guide edge when your spacing needs to remain 6.2MM. for 1/4" tape? It doesn't look like you use the white ceramic edge guides, as on the tension arms, for the tape guides.

BTW: When I state "With an attempt to cut into the guide is made it chips." I meant the edge guide, not the cutter.
Title: Re: Otari fixed guides
Post by: ironbut on September 10, 2011, 05:57:18 PM
Hi Neal,

I think the reason for having to take the fixed guides apart is the change to rolling guides. If you look at the pictures on the TP home page you'll notice that there's a line in the middle of the guides. This is where the two bearings meet.
Reducing the friction caused by the fixed guides make a very audible improvement particularly in the highs frequency response (decreases scrape flutter).
Title: Re: Otari fixed guides
Post by: Listens2tubes on September 10, 2011, 06:16:06 PM
Yes, but this discussion is about the black edge guides that are changed to silvery nes in the pix of the modded 5050. Those silver looking edges should be the same size as the black ones, unless the 6.2mm spacing is not a close enough tolerance for 1/4 inch tape handling. 
Title: Re: Otari fixed guides
Post by: docb on September 11, 2011, 10:59:35 AM
The five piece black and stainless guides (stainless spacer, black edge guide, center bushing, black edge guide, stainless spacer) are on earlier Otaris. Steve is correct that the black and silver guide has to come apart to install the ball bearings, and we reuse the black edge guides. It's a PITA because of the threadlocker used to hold the stock guide together. What is shown on the web page is ball bearings and the black edge guides. Perhaps they look silvery, but they are the stock black edge guides, only the center part is modified.

There are also one piece fixed stainless guides, which are used on later Otari models (some B-IIIs only, I suspect). Perhaps this is the source of some confusion. We tried to come up with a ball bearing replacement for those one piece guides using some stainless spacers, the ceramic washers we use on other guides and the two bearings. Spacing worked out fine, but unfortunately the ceramic washers can't take a lot of compression and they tend to crack you mount it all back on the machine and tighten the mounting screw. At this point we don't have a viable replacement for the later solid guides other than finding a set of the old five piece ones and modding them.
Title: Re: Otari fixed guides
Post by: Listens2tubes on September 11, 2011, 12:58:41 PM
Thanks Dan and Steve. I think the terminology is getting in the way. Dan's breakdown of the parts sorted out my misunderstanding of the words and pictures. Shiny stuff never reflects it's true look.

So I have one guide apart in three pieces. Stainless spacer with black edge and 3 x 6mm threaded rod - center bushing -  stainless steel spacer with black edge. Yes that thread lock is freakin tough. We had the locked in the lathe and used a pump pliers. The stainless on the pliers end got marred but not mangled and would be fine in the bottom position since the marks are more to the other end. Still having a lathe is helpful in not marring both ends since this is a herculean effort. An of course the lathe could be used to clean up the spacers if needed.
Title: Re: Otari fixed guides
Post by: Listens2tubes on September 13, 2011, 05:33:19 PM
 OK so I took the other 2 apart. This time I chuck it in the lathe and used a small vice grip, which was able to be clamped then spun without having to release it. It did not leave a mark on the spacer. They come apart fairly easily.

 I think the thread lock is the glue that holds the black guide edge to the SS spacer. As evidenced by one that came apart: stainless spacer then black edge guide and so on. There was more thread lock on the tape side of the black guide than the SS spacer. I think the thread lock was put on the rod before the black guide was threaded on instead of between the black edge guide and SS spacer. Removing the tread lock from the treaded rod was a bit of work with the brass brush I used, but did clean off well. Using the threaded rod to work the excess goo out of the threads worked fine.
 So for everyone to do this two vice grips could be used. A large one and a small one, where the large vice grip is clamped in a vise and the smaller is used to turn the other sections off. Note it is easy to flex the threaded rod being it is a 3x6mm thread and 3mm is just shy of an 1/8 inch. So try to turn the tool like a knob from as close to it's center as you can once the initial few loosening turns.

Now who will be first? Me?
Title: Re: Otari fixed guides
Post by: Listens2tubes on September 07, 2012, 09:29:53 PM
Well finally after too much time having the kit I've installed the bearings. Funny thing, I didn't want to open the machine and unscrew the tape guide posts. So I first thought of trying a tap handle, but it is only for a square shank. Then the brainstorm blew in. I grabbed my 1/2" drill. Chucked the left post up, hand tightened it and hit reverse. BINGO! everything but the base section unscrewed together. This worked for all three, easy as pie. :-) Still having the guides I took apart above made the job easier yet. All i had to do was load the spacer, bearing, spacer, bearing, spacer onto the screw and assemble it back to the base of the guide still on the machine. Wish I took pix. *thumbsup*
Title: Re: Otari fixed guides
Post by: Listens2tubes on January 26, 2013, 08:01:12 PM
Have been playing tapes today. Noticed there is a wrrring sound coming from the deck. In the past I suspected the capstan but discounted the idea since the machine recently came back from JFR. It seems the rollers are each wrrring at a different pitch. While a tape was finishing in silence I held the right arm and pulled the tape away with the back of my finger. The WRRR became much quieter. So with the tape packed away I took a pencil and used the eraser to spin the last three bearings, they all spin madly along with different pitches of wrrring. Did I miss a lube step in the assembly process?
Title: Re: Otari fixed guides
Post by: docb on January 27, 2013, 12:46:45 PM
I have only noticed the sound in fast wind. In play the decks have always been quiet.
Title: Re: Otari fixed guides
Post by: Listens2tubes on December 15, 2013, 06:11:55 PM
At 15ips the zzzz of the tension arm w/safety switch is loud enough to be heard during music playing. That's with me sitting at the listening position. The deck is behind me 7-8ft and on the opposite side of the wall to the left of a large door opening. Is there a way to lube these tiny bearings? Am I missing something?
Title: Re: Otari fixed guides
Post by: docb on December 16, 2013, 02:39:12 PM
Cleaning the guides with lots of alcohol can sometimes remove the lubricant that is sealed inside the ball bearings and that can make them noisy. We have seen this happen on one or two other decks. Normally I don't hear that sound except in fast wind and since you are only hearing one of the guides that may be what has happened. If that is the case the solution is probably replacement.
Title: Re: Otari fixed guides
Post by: slorinczi on September 20, 2014, 02:06:44 PM
Rereading the previous posts carefully, it sounds like brute force--and perhaps acetone?--is the way to go with these early guides?