6in or 8in Bench Grinder? Power, Wheels and Vibration Sorted

Choosing between a 6in and an 8in bench grinder, or stuck with one that shakes, slows under a chisel or will not take a new wheel? It usually comes down to three things: wheel size, the motor’s continuous rating, and how the wheels are fitted and dressed.

The metal bench grinder range at PartsForMachines has 40 products, including 26 Sealey, Draper and SIP bench grinders, plus sharpeners, belt linishers and a floor stand.

6in or 8in: Which Bench Grinder Size Do I Need?

Pick a 6in (150mm) grinder for occasional sharpening and light metalwork, and an 8in (200mm) model if you grind often, remove a lot of metal or work on wide tools. The bigger machines usually have wider wheels (25mm, against 19–20mm on most 6in models), a larger spindle and more power. Most 8in models are rated at 550–600W, while 6in dry grinders run from 150W to 450W.

The 07628 8in bench grinder has 25mm-wide wheels on a 16mm spindle and is sold as 550W (370W continuous).

Is 150W Enough? How Much Power Does a Bench Grinder Need?

For occasional sharpening a small 6in grinder will do; for long sessions or heavy grinding, compare the continuous (S1) rating, not just the headline watts. Some small motors are meant for intermittent use: the 150W BG150CX is rated S6 40%.

The headline figure can be a short-time rating, too. The 07625 6in bench grinder is sold as 370W, which is its 30-minute (S2) rating; run continuously (S1), it is rated at 250W.

If a grinder slows when you lean on it, ease off rather than force the work.

Bench Grinder Vibrating? What Should I Check First?

Start with the wheels and the mounting, the parts you can put right yourself. Dress both wheels true. Then, with the grinder unplugged, check each wheel sits between clean, matching flanges with a blotter each side. Never leave a wheel standing in liquid, as that can upset its balance.

Finally, bolt the grinder securely to a solid bench or a stand such as the SM57/ST floor stand. It is made for ten Sealey grinders and also suits some other makes, though its top plate or frame may need modifying.

Which Replacement Wheel Will Fit My Bench Grinder?

One that matches three things: the diameter and width your grinder is made for, a bore that suits its spindle, and a maximum speed, marked on the wheel, at least as high as the grinder’s. Most of our bench grinders run their dry wheels at 2,850–3,000rpm.

Spindles are usually 12.7–13mm (½in) on 6in grinders and 15.8–16mm (⅝in) on most 8in models. Replacement wheels often have a 31.75mm (1¼in) or 32mm bore and come with reducing bushes, so check your size is in the set. The wheel should slide on freely: never force it or enlarge the hole.

What Should I Check Before I Buy?

• the wheel size, 150mm or 200mm, and how wide a face your work needs
• the continuous (S1) or duty rating, not just the headline watts; ask us if none is shown
• the spindle size (12.7–13mm, 15.8–16mm or 20mm), so spare wheels and bushes will fit
• eye shields, adjustable tool rests and a no-volt release (NVR) switch, which stops it restarting after a power cut
• how it mounts (bolt holes or a floor stand) and extras such as a wire wheel, work light, water tray or built-in dresser

Not sure which grinder suits your work? Browse the metal bench grinder range or contact the PartsForMachines team by WhatsApp, telephone or email with what you grind and the spindle size of your old grinder.

Product options, delivery options and returns terms are shown on each product page. A 30-day return policy applies to eligible items.

Frequently Asked Questions

How tight should the wheel nut be?

Just tight enough to hold the wheel without it slipping. Do not over-tighten it, as that can damage the wheel and flanges. Once the wheel is on, stand to one side and let it run for at least a minute before you start grinding.

How do I check a new grinding wheel for cracks?

Ring-test it before fitting. Hang the dry wheel on a pin or finger and tap it gently with a screwdriver handle. A clear ring means it is sound; a dull, dead sound means it may be cracked, so do not use it.

Do I need the paper washers on each side of the wheel?

Yes. These paper washers, or blotters, go between the wheel and each flange, one on each side; use the ones supplied with the wheel. The two flanges should be the same size, clean and flat, and a worn or warped flange should be replaced.

How often should I dress a grinding wheel?

Regularly, and whenever the face shows chips, flat spots or glazing. A dresser cleans, sharpens and trues the face: the BG150WL bench grinder has one built in, and the 05097 comes with one.

How close should the tool rest be to the wheel?

Safety guidance sets no more than 3mm (1/8in), with the adjustable upper (tongue) guard within 6mm (1/4in). Adjust both only with the wheel stopped, reset them as it wears, and replace the wheel once the rest can no longer close the gap.

Which wheel should I use for HSS tools or carbide?

Match the abrasive to the tool. White aluminium oxide wheels are made for sharpening HSS, and the 78456 wet and dry grinder’s dry wheel is a white stone meant for HSS tooling. For carbide-tipped (TCT) tools, look for a silicon carbide wheel made for them.

Can I grind aluminium on a bench grinder?

Not on an ordinary grinding wheel. Use a belt instead: the 01960 4in belt linisher handles mild steel, aluminium and stainless steel on a 230V single-phase supply. Otherwise, use a wheel whose label says it suits non-ferrous metals.

Wet and dry grinder or a standard one for chisels and knives?

A wet and dry grinder gives you both: a slow wet stone for fine edges and a fast dry wheel for removing metal. The SM521 wet and dry grinder turns its 200mm wet stone at 130rpm and its 150mm dry stone at 2,850rpm.

Is a variable-speed bench grinder worth it?

It can be, if you sharpen as much as you grind. The BG150WVS and BG200WVS turn down to 2,000rpm, and Sealey says variable speed gives better control of grinding and sharpening. Both have a built-in coolant tray.

Is a wire wheel worth having on a bench grinder?

Yes, for cleaning rust and scale off metal parts. The BG150XLW/98 pairs one stone with a wire wheel, and the 07625 and 07628 come with a wire wheel as well as two stones. Wear eye protection whenever you use one.