Mixing Paddle — 85 mm Helical Paddle

• Art. Nr: 390501
• Size: 85mm blade, 8mm shaft, 500mm length; rated 5-15kgs per batch
• Construction: Helical open-loop blade on an 8mm shaft for a standard drill chuck
• Handle: None, the drive end is the shaft itself

Product Name & Model

Mixing Paddle — 85mm Helical Paddle, 8mm Shaft, 500mm

Art. Nr: 390501

The Mixing Paddle is a single-specification product: one art number, 85mm blade diameter, an 8mm shaft, 500mm overall length, rated 5-15kgs per batch. It sits between the Wire Mixer and the Plaster Mixer in the Leading Tools mixer range.

Identify the model by all four specification figures, not by blade diameter alone: the Wire Mixer 390401 also has an 85mm blade on an 8mm shaft, but it is 400mm long and rated 5-10kgs. Blade diameter and shaft size do not separate the two products; length and rated capacity do.

Core Features

One specification, no variants to get wrong. 85mm blade, 8mm shaft, 500mm length, 5-15kgs rated capacity: a single art number covers the whole product. There is no diameter choice, no connection choice and no length choice to specify on the purchase order.

Helical open-loop blade that lifts the batch from the bottom. The blade is a helical paddle with open loops rather than a closed cage or a flat ribbon. The working action is turning and lifting the mix from bottom to top, which suits dense, viscous materials such as plaster and mortar.

8mm shaft: runs in the drill you already own. The connection is an 8mm shaft that clamps in an ordinary drill chuck, so no dedicated M14 mixing machine is required. M14 is the most common connection on professional mixing equipment, and it is the connection you step up to when you outgrow this head: in the Leading Tools range that means 390402, 390211 or 390212.

500mm of reach. 100mm longer than the Wire Mixer 390401 (400mm) and 100mm shorter than Wire Mixer 390402, Plaster Mixer 390201 / 390211 / 390212 and the mid-size Spiral Mixing Paddles (600mm). That is enough shaft to reach the bottom of a standard builder's bucket while keeping the chuck clear of the rim.

Rated 5-15kgs: the middle rung of the Leading Tools mixer range. Below it, the Wire Mixer family stops at 10kg and the smallest Spiral Mixing Paddle starts at 1kg; above it, the Plaster Mixer family runs to 40kg. The rating is specified per art number, so selection is arithmetic rather than judgment.

One head for several thick materials. Helical paddles of this class suit thicker materials such as gypsum plaster and cement repair mortar, so a single 85mm head can cover plastering and patching without a tool change. For tile adhesive, self-levelling compound, epoxy resin, paint and other special materials, follow the material manufacturer's mixer recommendation.

Product Advantages

It closes the gap between a grout whisk and a plaster mixer. Moving up from the Wire Mixer's 5-10kgs otherwise means jumping to 390201 at 120mm blade / 12mm shaft / 600mm / 5-25kgs: a bigger blade, a bigger shaft and a machine to match. 390501 raises the batch ceiling to 15kg while keeping the 85mm blade and the 8mm shaft, so the drill and the bucket stay the same.

No dedicated mixing machine required. An 8mm shaft runs in a standard drill chuck, which keeps the entry cost to the price of the paddle. That matters in rental fleets and where an M14 mixing machine is not a default purchase, even though M14 is the professional standard connection.

Bottom-to-top action rather than stirring. A helical paddle drives material along the axis of the shaft, not only around the bucket, so thick material does not pack at the bottom.

500mm is the length that fits both bucket sizes. With 500mm of shaft, the same head works in a small pail and in a standard builder's bucket without the operator having to tip the container to reach the bottom.

A clear ceiling. The rating is 5-15kgs. With drill-driven mixing, the limit is the machine as much as the paddle: use a drill with enough torque for the batch, and move to a dedicated mixer for sustained heavy work.

Small-to-medium batch tool. At 85mm × 500mm and rated 5-15kgs, this is a small-to-medium batch tool.

How to Use

When to use: material to suitability

For tile adhesive, self-levelling compound, epoxy resin, paint and other special materials, follow the material manufacturer's mixer recommendation.

Basic technique

Mixing speed

There is no single speed figure for drill mixing, so follow the material manufacturer's instructions. Start low, raise only after wet-out, and reduce speed the moment the batch splashes or foams. Behaviour, not the tachometer, is the control that matters at this scale.

Container selection

Size the container so that the 85mm blade turns clear of the wall and so that the 500mm shaft reaches the bottom without the chuck entering the container. A batch inside the 5-15kgs rating in a standard builder's bucket is the working case this head is built for.

Scenario: plaster, patching and repair mortar

Helical paddles are the right type for plaster and repair mortar. Keep the batch inside 15kg, keep the speed low so the finish is not aerated, and pre-blend dry constituents before adding water if you are combining more than one powder, so the paddle is distributing an already-uniform powder rather than dry-blending under water. Quick-setting patching compounds leave no room for a second attempt: measure the water, have the container and the tools ready before the powder goes in.

Scenario: angled and overhead work

An 8mm shank in a drill chuck depends on clamping friction alone, so confirm the chuck is fully tightened before every start rather than once per session when the paddle is not vertical and below the machine. Support and steady the drill with the second hand during angled work. For sustained overhead cement work, a threaded M14 connection is the safer arrangement, and in the Leading Tools range that means 390402, 390211 or 390212.

FAQ

Q1. What exactly do I get when I order 390501?
A: One 85mm helical mixing paddle on an 8mm shaft, 500mm overall, rated 5–15kgs per batch. It is the only art number in the Mixing Paddle family, so there are no variants to specify. A helical paddle puts a solid blade face through the batch and suits heavier material than a cage paddle.

Q2. How is this different from the Wire Mixer 390401?
A: Length and rating: 390501 is 500mm and rated 5–15kgs, while 390401 is 400mm and rated 5–10kgs. For grout-only work 390401 is the purpose-built head; for plaster and repair mortar, 390501 is the better choice.

Q3. How should I mix?
A: Put the liquid in the container first, then add the powder gradually, starting at low speed until the powder is wetted out. Follow the material bag for speed, and reduce it if the batch splashes or foams. If you find dry lumps at the bottom, check the order (water first), the speed (too low and the batch does not circulate) and the batch size (not above 15kg).

Q4. What drill do I need, and can I mix 20kg in one batch?
A: Use a drill with enough torque for the batch size. Not 20kg with this head: the rating is 5–15kgs, so for 15kg and above step up to the Plaster Mixer, 390201 (5–25kgs) or 390211 / 390212.

Q5. How do I look after the paddle?
A: Wash it immediately after each batch rather than leaving it standing in the material, because cured material changes the blade profile and balance. Soak dried residue in warm water instead of chipping it off with metal tools. Replace the paddle when the helix is bent, the edges are visibly worn or the shaft no longer runs true.

Specifications Overview

Specifications

In inch terms, 85mm is 3.35in and 500mm is 19.7in (1in = 25.4mm).

Blade design

The head is a helical paddle: a spiral blade forming open loops around the shaft axis, without the closed wire cage of the 390401 Wire Mixer and without the flat ribbon of a ribbon-type mixer. The functional consequence is that the paddle turns and lifts material from the bottom of the drum to the top rather than only rotating it, which suits dense, viscous materials such as plaster and mortar.

Compared with the Wire Mixer, the difference in the bucket is shear. A cage disperses powder with minimal shear and minimal air pick-up; a helical blade puts a solid blade face through the batch on every revolution and therefore works heavier, more viscous material. Compared with a large plaster mixer, an 85mm helical head has less blade area, so it moves less material per revolution and needs less torque from the machine.

Connection design

The connection is an 8mm shaft that clamps in a standard drill chuck.

What governs use is the load path. A drill chuck transmits torque by clamping friction on the shank, so grip degrades as the jaws wear, and sustained heavy mixing is exactly what wears them. That is also why M14 is the professional connection for mixing duty: a threaded joint carries torque mechanically. In the Leading Tools range, M14 is available on 390402 (Wire Mixer, 105mm) and on 390211 / 390212 (Plaster Mixer, 120mm / 140mm).

Why 85mm and 500mm

Across Leading Tools' mixing heads, 390501 is the point where blade diameter stops growing (85mm, same as the Wire Mixer 390401) but shaft length and rated capacity both step up (400mm → 500mm, 5-10kgs → 5-15kgs). Paddle selection rests on exactly these two variables: match the paddle to the batch volume and to the driving machine, and there is no universal diameter-to-kilogram table, so the rated figure is the number to design around.

There is no handle on this product: the drive end is the shaft itself, and the operator's grip is on the machine.

Selection Guide

Step 1: Confirm the machine before the paddle

390501 has an 8mm shaft and no M14 option, so it is a drill-driven paddle by definition.

• You will drive it with a drill → 390501 is specified for that. Use a drill with a chuck that takes the 8mm shaft and enough torque for the batch size.
• You already run a dedicated M14 mixing machine → do not buy down to an 8mm shaft. The M14 options in the range are 390402 (105mm, 600mm, 5-10kgs), 390211 (120mm, 600mm, 15-25kgs) and 390212 (140mm, 600mm, 25-40kgs). M14 is the connection professional mixing equipment is built around.

Step 2: Match the rated capacity to the batch you actually mix

Step 3: Match the blade type to the material

Helical paddles are the type for thick materials such as plaster and repair mortar. For grout and filler, the Wire Mixer 390401 is the purpose-built choice, and it is rated for the smaller batches that grout work usually involves. For tile adhesive, self-levelling compound, epoxy resin, paint and other special materials, follow the material manufacturer's mixer recommendation.

When to choose 390501

Choose 390501 when your work is plaster, cement repair mortar and light plastering in the 5–15kg range; when you drive the paddle with an ordinary drill rather than an M14 machine; when you want one head that covers several materials across a workday; and when your containers are standard builder's buckets rather than drums.

Choose 390401 (Wire Mixer) instead when you work almost exclusively with grout, joint compound and similar low-viscosity air-sensitive materials, when your batches stay at or below 10kg, and when you do not need the extra shear of a solid blade.

Choose 390201 / 390211 (Plaster Mixer) instead when you regularly handle batches above 15kg, when the material is heavy cement, mortar or render, and when you have a drill with a 13mm chuck (for the 12mm shaft) or an M14 machine to drive the larger blade.

Choose the Spiral Mixing Paddle family instead when you need either a smaller head than 85mm (390601, 60mm, rated 1-5kgs) or a longer reach than 600mm (390605, 760mm).

Common selection mistakes

Ordering 390501 for heavy cement work. For sustained heavy cement, mortar or render, the family is the Plaster Mixer.

Ordering 390501 when grout is all you mix. 390401 shares the same 85mm blade and 8mm shaft, is rated for the batch size grout work usually needs, and a cage disperses powder with less shear.

Confusing 390501 with 390401 on a thumbnail. Both are 85mm on an 8mm shaft. The separating figures are 500mm / 5-15kgs versus 400mm / 5-10kgs. Specify the art number on the order, not "the 85mm one".

Using a container that is too narrow. A blade running close to the bucket wall vibrates, wears at the tips and circulates the batch badly rather than mixing it. Size the container so the blade turns clear of the wall.

Which of Leading Tools' four mixing families?

Full Size Reference

Complete art-number reference for the Mixing Paddle family.

One art number, and no variants. Units are mm and kgs; 85mm is 3.35in and 500mm is 19.7in at 1in = 25.4mm.

Attribute view of the same model:

Related art numbers elsewhere in the Leading Tools mixer range, for cross-reference when 390501 is not the right rung:

Care & Maintenance

Cleaning after every batch

Wash the head immediately after mixing, while the material is still wet. Cementitious and gypsum materials cure on the blade, and once cured they change the blade profile and the balance of the head.

Practical routine: run the paddle in a container of clean water at low speed to flush loose material, rinse under running water, then finish with a nylon brush, paying attention to the inside of the blade loops and to the junction between blade and shaft where material collects.

Soak dried residue in warm water before brushing rather than chipping it off. Remove dried residue with a plastic scraper or nylon brush; do not use a steel brush, metal scrapers or abrasive pads, which scratch the surface. Dry the head before storage.

Inspection before use

• Blade surface. Look for chips, cracks and damage.
• Blade shape. A bent or opened-out helix runs untrue, vibrates and circulates the batch badly. Replace rather than straighten: straightening changes the balance of the head.
• Blade edges. Wear concentrates at the outer edges of the loops, which is where sand-loaded materials abrade first.
• Shaft. Check the 8mm section for deformation and for bright rub marks where the chuck jaws have been working. An 8mm shaft is thinner than the 10mm and 12mm shafts elsewhere in the Leading Tools mixer range and correspondingly easier to bend, so treat any visible run-out as a reason to replace the paddle.
• Chuck. If other bits run true in the same chuck and only the paddle vibrates, the paddle is the variable; if everything runs untrue, the chuck is.

Storage

Store dry. Hang the paddle vertically or lay it flat with no load on the blade, and do not stack weight on stored paddles. For long storage, a light oil film on the shaft limits surface oxidation.

Operator safety

Do not wear loose gloves when operating rotating tools: general power-tool safety instruction is that gloves can be caught by rotating parts, with finger and thumb injuries as the result.

Wear eye protection: powered mixing of dry powders throws both dust and splash, and the highest-exposure moment is the transition from wet-out to working speed.

Keep the machine's speed control under positive control before the head enters the container; starting at working speed with the head already submerged is how containers get thrown. Use a drill with enough torque for the batch size; an overheating machine is itself a hazard.

Service life

Service life depends far more on material abrasiveness and cleaning discipline than on calendar age. The two factors that shorten it are high sand content, which abrades the blade edges, and material left to cure on the blade, which changes the profile. Replace the paddle when the helix is visibly bent, when the blade edges have worn enough to change how the batch circulates, or when the shaft no longer runs true in the chuck.