How to Replace a Scarifier Cutting Drum

Once you have operated your scarifier for a while, your Scarifier Cutting Drum requires regular replacement. Your manufacturer’s manual is helpful to understand this procedure, but we tell you necessary steps on how to replace your Scarifier Drum. By following four steps of this method, you will be able to change your drum smooth and efficiently. The main four steps are: Removing the cutting drum, disassembling the cutting drum, assembling the cutting drum, and installing back the cutting drum. Due to the complex process that takes these phases, we will break it into simple steps. Follow these instructions to have your scarifier ready for operation.

A)    Cutting Drum Removal:

1.    Rotate the scarifier to rest on the handle bar.

Note: Never rest on the back of the handle bar

2.     Find the shaft cover, and retaining screws. 
3.     Remove the shaft cover and cage, use 9/16 wrenches and/or sockets to rear retaining bolt and loosen the front retaining bolt.
4.     Remove the shaft, retaining plastic cover from belt guard and expose the shaft. 
5.     Use a 15/16-inch socket to loosen the outer shaft.

Note: Rotate counterclockwise.

6.    Remove the outer shaft while using your index and middle finger to pull the retaining nut. (show below* missing pictures)

Note: Repeat step 6 for the inner shaft, and also the retaining nut.

7.    Take out the Cutting drum as shown, by pushing it away from the belt side and removing the shaft. 
 

B)    Cutting Drum Disassembly:
1.    Find the retaining ring and retaining screws from the cutting drum edges.
2.    Use a 7/16-inch wrench to remove the 3 retaining screws.
3.    Remove the drum retaining ring and the three flat washer spacers 

 Note: Place these elements at a safe location.

3)    Cutting Drum Parts + Assembly :


Before assembling the cutting drums, there are few factors to look at on each side of the retaining plates: Wide and narrow side. Additionally within these plates is possible to accommodate three main components: 

1) Hardened steel shafts.
3) Hardened steel spacers.
2) Drum cutters. 


We will take a look at both main two assemblies: Flat tip drum assembly for general purposes, and Tungsten carbide for more aggressive finishes. Let’s look at few components to keep in mind:


Shafts: Also called “bars” or “handles” have the function to accommodate the most common cutting discs or cutters. For the case of 8-inch long cutting drums, there are 6 hardened steel shafts supported by two retaining plates and one middle plate.
 
Spacers: This tool allows cutters to have enough movement between each other cutter, but not too loose. To test the space balance of your drum, ensure all cutters can spin without tighten up too much. In case there is too much space could cause premature wear and possible early Cutting Drum damage. Scarifier drums must be balanced enough to spin freely, otherwise, if it is too loose, you can add either one cutter or one spacer to the shaft. 


Drum Cutters: Also called “Cutting Discs” or just “Scarifier drum cutters.” This tool defines the type of surface finish you are looking for your job site. We recommend revising the drum cutter conditions before assembling them into the shafts. Check these are not excessively worn and not missing tips. There are several types of cutters with different features. Some cutters have longer lasting than others depending on the material. We will briefly mention three primary kinds of cutters. To learn more about their main function, check our blog on “Scarifier Cutters”

•    Steel Scarifier Cutter: The most economical cutter for long-lasting smooth finish. Ideally used for light preparation projects related to coating applications or removal of surface materials. Also useful for general purposes such as cleaning 
•    Milling Scarifier Cutter: utilized for removing thick and soft materials including but not limited to, waterproofing membranes, plastic coatings, glues, etc. Milling cutter can also remove traffic lines, epoxy, and other general scarification. 
•    Tungsten Carbide Cutter (TCT): Exceptional life and was designed for heavy-duty scarifying purposes. This cutter works for extremely aggressive tasks such as grinding, leveling, grooving, cleaning and other general surfaces. Let's look at the steps to assemble a 6-tooth tungsten carbide drum for general purposes:  


1.    Remove the drum’s retaining plate: 
2.    Assemble the cutting drum following this procedure: 

a.    Take out the wider side of the first shaft. 
b.    For the edges of the wide side add 5 steel spacers, and 1 carbide cutter.
c.    Add 2-3 spacers and 1 carbide cutter to the shaft.
d.    Once you are reaching to the middle ending part of the shaft, add 4 cutters.
e.    Finally add 1 to 2 spacers.

Note: Make sure all cutters spin freely, remove a spacer if it feels too tight. 

3.    Assemble the narrower side of the shaft by adding 2 spacers: 

f.     Add 1 carbide cutter and 3 spacers.
g.    Add 1 cutter and add 3 spacers, repeat this procedure for the next round.
h.    Finally add 1 to 2 spacers. 

4.    The next shaft has the reverse pattern of the first shaft. Make sure to balance the drum the same way as the reverse part to ensure all the cutters impact the surface while working on the scarifier. 
5.    Close the cutting drum with the retaining ring and flat washer spacers. 

Note: Make sure to install the retaining ring. 


4)    Cutting Drum Installation:


1.    Install cutting drum by aligning it with the shaft-side bearing. 

Note: Check the cutting drum and shaft are fully assemble inside the scarifier.

2.    Install the inner retaining nut located on the shaft.
3.    Use a 15/16-inch socket to tight the shaft, inner retaining nut.

 Note: Rotate the shaft counterclockwise.

4.    Once the shaft is installed, place back the retaining nut onto the belt guard. 
5.    Pivot the shaft guard cover and install the rear retaining screw.

These steps will get easier to follow once you understand the essential components of your concrete scarifier. Follow the four stages to replace your cutting drum, and make sure to get the right drum cutters, which will determine your surface finish. Don’t forget to choose the correct type of cutter for your job. Also, keep record of the drum cutter life, and the use frequency within the scarifier. Check the new set of cutters is under right conditions without missing tips. 

Be sure cutter drum is balanced, with the same number, size and correct cutters. It is necessary to bounce your drum, in order to prevent malfunction and possible premature wear. It can be tricky and time-consuming finishing the edges or corner of the retaining plate. Indeed after practicing with the rest of the shafts, you will achieve a balanced and free of spin drum ready to operate.