GBC 450-KM Binding Machine Maintenance and Controls

GBC 450-KM binding machine: Maintenance is required for smooth and reliable function

GBC 450-KM binding machine: Maintenance is required for smooth and reliable function

All machines need maintenance or they will break down. My GBC 450-KM binding machine is no exception. My machine uses common plastic combs, will punch comb rectangles and bind into a booklet of varying thicknesses. Given use it will jam and will refuse to bind, so you need to open it up, trouble shoot, tighten and grease. The user manual also does not fully explain the left side controls of the machine nor any maintenance, so I thought I would embellish here.

The GBC 450-KM instruction manual covers a little of this post but is insufficient, especially for general maintenance.

Control Instructions

The Binder control knob on the left side has two controls:

  1. The ABC control is activated by pushing the knob in and turning. This controls the distance between the rectangular holes and the edge of the page. Setting “C” is 16mm and above. Setting “A” is 5-10mm. I always use setting “C”.
  2. The 1-9 control is the Back Guide Control Knob. This adjusts for small and large combs. At the higher setting the combs bend back very far in order insert large amounts of paper.


I have had to do the following:

  • Comb control mechanism separated from handle mechanism
  • Grease the comb mechanism

From the bottom of the machine at each far corner you will see four bolts with an indented allen key round head. These bolts will have a lock and circular washer. You will need a hex or allen key to remove them. Remove all 4 bolts. In the middle of the machine there are lots of other bolts, some slot head some hex head. You need not remove these, as they bolt the machine to its base.

Remove the handle by rotating it counter clockwise until it comes off. Remove the Binder control knob on the left side. The outer part simply pulls off. The inner knob requires a 2.5mm allen key. When reinstalling this allen key ensure it firmly seats itself into a circular hole. The top cover should become loose.

To remove the binding mechanism there are two additional bolts to remove. The first is a “+” bolt, located on the right side where the arm goes down. Remove this and an “L” shaped piece of metal will fall out. This tightens the comb mechanism to the rear right of the cover. The second is located on the rear left corner of the machine, visible from underneath. This is a slot head bolt and is difficult to access. You will need a long handled screwdriver. Remove this and a flat piece of metal with a small right angle will fall out, which tightens the comb mechanism to the rear left of the machine. Remove the two “+” head screws on top of the comb mechanism. Jiggle the comb mechanism out, which is difficult. Be persistent. It does remove.

Once you remove the comb mechanism you will see the large axle in the middle. This connects to the comb mechanism through a pair of forks. These two forks have no return mechanism and simply stay in place through friction. When you move the arm you will see these forks engage the main axle. Tighten these two forks until they stay in place due to friction. If these forks loosen and drop down due to gravity you will have lost control of the comb binding mechanism and will not be able to bind. Grease the two knobs where the main axle meets the cutting mechanism. Grease the forks.

The comb binding mechanism is a group of three sliding pieces of metal. The first is a long narrow piece that interacts with the two forks near the main axle. For all three pieces, grease the tops and bottoms where the metal slides against each other. I used automotive bearing grease that has a light translucent colour. Put the three layers back together.

Inserting the newly greased comb binding mechanism back into the top is difficult. I will forgive anyone who curses. Firstly slip the whole mechanism into the machine top cover. It is a very tight fit. Slip the long edge, the one opposite the comb fingers, between the plastic cover and a metal bar underneath. If you fail to do this the three metal layers will not stay together. Reinstall the two metal brackets you removed from the left and right rear sides of the machine. The “+” bolt on the right is easier. You will need slim hands to do the one on the left rear, or maybe some adhesive on your screwdriver. My daughter slipped her dainty digits into the damn small opening, bless her sweet heart. Tighten down those and the two “+” head bolts on top of the comb mechanism.

The next thing to do is to mate the two fingers near the main axle with the comb mechanism. One is on the left and one is on the right. Take your time because they are tricky. Look from the bottom. Because the cover is loose you can see better, but the fit is still tight. Once the two fingers are mated to the comb mechanism, try the binding handle. If the comb mechanism comes alive you are good, otherwise try mating again.

Reinstall the four indented allen head bolts on the far corners of the bottom of the machine. Reinstall the left side control mechanism and the handle. Your comb mechanism should slide very easily and will not bind up and refuse to move. You are done.

Overall this machine is solid and will last many years. Apart from the outer cover the mechanism is all metal. With maintenance and a lack of physical abuse I am very happy with its function. I am sure you will be happy as well. I have not needed to maintain the cutter mechanism, but if I do I will amend this article.

GBC 450KM3 User Manual

GBC 450KM3 User Manual


GBC 450-KM binding machine: Maintenance is required for smooth and reliable function

2 thoughts on “GBC 450-KM Binding Machine Maintenance and Controls

  1. Robin Roeckers

    Hello, I work for the City of Topeka, Kansas and I have a problem with GBC 450KM-2 which I have been working with for MANY years. It has recently begun binding up in the comb expansion process so I have dismantled it. I have followed your excellent narration on how to dismantle the machine. I’ve cleaned it and lubricated where you mentioned and now I am putting it back together. I have hit a snag. I can’t seem to get the red tabs to mesh with their metal counterparts once I’ve realigned the adjuster part with the hole in the side of the top. Is there a trick to this?

    [Don: Hi Robin, and thanks for stopping by. It has been three years since I maintained my binding machine and cannot remember any tricks to getting the red tabs in their proper place. Reexamining my binding machine did not tweak any distant memories. I do recall that the order of reassembly was very important. Try meshing the red tabs first, then putting everything else together. I also recall that even though I have small hands I needed help from my daughter, with her long, thin and dainty digits, to get it put together.

    Good luck and good for you to maintain this solid piece of machinery instead of buying new. We need more people that can fix things! Just a note that the new GBC binding machines are not made as well as the one you have.]

  2. Tony Smith

    I assume the red tabs are the tabs that control the cutter positions. It so try putting the red tabs into the brown frame first, have them flush with the front edge, then drop the frame and tabs over the metal tabs, then push the tabs in and push the frame back into place. you may have to remove the paper stop to get more space.

    Hope this helps.

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