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Adjustable reamer 74-84 mm NRZe
226062
€207.16 tax inc.
Net price: €168.42
Description
Adjustable reamer 74-84 mm – adjustable, with a 40 mm square
Technical data – HSS blades, shank with square drive for a tap wrench
| Technical data | |
|---|---|
| Adjustment range | 74–84 mm |
| Designation | NRZe to PN |
| Blades | HSS, in inclined grooves |
| Diameter adjustment | two nuts |
| Shank diameter | 50.0 mm |
| Shank square | 40 mm |
| Overall length | 400 mm |
| Blade length | 123 mm |
| Drive | tap wrench |
Adjustable reamer 74-84 mm NRZe finishes holes of any diameter from 74 to 84 mm. Set the diameter with two nuts that move the high-speed steel (HSS) blades in the inclined slots in the body. The shank has a diameter of 50 mm and a 40 mm square for a large tap wrench. Drills in this range are available in 1 mm increments and leave too much allowance. Therefore, bore the initial hole 0.05–0.15 mm smaller than the finished size.
Manufacturers design adjustable blade reamers for repair and assembly work. They are useful wherever a hole needs to be fitted to the part at hand. The diameter is then set to the size of the part, rather than to the standard size series of fixed reamers.
Which size to choose: 74-84 or 70-85 mm
Two reamers cover holes from 74 to 84 mm: 74-84 mm and 70-85 mm. Both have a 50 mm shank and a 40 mm square, so they use the same tap wrench. The 70-85 mm reamer also covers holes from 70 to 74 and from 84 to 85 mm. However, it is 110 mm longer, 510 versus 400 mm, and its blades are 22 mm longer. The 64-74 mm reamer extends to 74 mm but has a 39 mm square.
How diameter adjustment works – blades and two nuts
NRZe reamer construction and measuring the diameter setting
The body has inclined grooves around its circumference, each holding an HSS blade. Two nuts, front and rear, retain the blades at both ends. Moving the blades along the grooves moves their cutting edges away from or toward the axis. This changes the cutting diameter over a range of 10 mm, from 74 to 84 mm. This is why the tool is also called an adjustable reamer.
Adjustment in three steps
First, loosen one nut. Then tighten the other — the blades will move to the new diameter. Finally, lock the blades by tightening the first nut. The rear nut, on the shank side, provides the main clamping force; the front nut is only snugged up. Tighten carefully. Excessive force bows the blades outward and causes the reamer to catch in the hole.
How to measure the set diameter
With an even number of blades, measure the diameter across two opposite blades using a micrometer. With an odd number, a groove lies opposite each blade, so the micrometer will read too low. In this case, use a setting ring or a hole of known diameter. Insert the reamer and expand the blades until they contact the hole wall.
How to ream step by step – tap wrench and clockwise rotation
Guidelines for using an adjustable hand reamer
Insert the reamer into the hole and apply light pressure so the blades engage the wall immediately. The tap wrench must fit the square closely to ensure smooth rotation without jerking. Align the reamer axis with the hole axis. For a longer hole, check the alignment with a square.
Hand reaming in six steps
1
Prepare the hole
0.05–0.15 mm smaller than the finished hole, e.g., 78.9 mm for 79.0 mm.
2
Set the diameter
Loosen one nut, move the blades with the other, then lock the first nut.
3
Fit the tap wrench
Fit it to the square and align the reamer with the hole axis.
4
Turn clockwise
Turn smoothly with light, even pressure.
5
Withdraw the reamer
Keep turning clockwise, including as the blades leave the hole.
✓
Check the hole
Too tight? Set a larger diameter and make a second pass.
Guidelines based on adjustable reamer manufacturers' instructions.
As the blades emerge from the far end of the hole, resistance drops suddenly. Reduce pressure at this point, but maintain the same turning speed. Otherwise, the reamer will jump through the end of the hole and leave it uneven.
▲
Never turn counterclockwise
Turning counterclockwise in the hole dulls the blades and may chip them. It can also loosen a nut and change the setting. Turn clockwise when withdrawing the tool as well; otherwise, you will scratch the hole wall.
How much material one pass removes
Reaming allowance and initial hole
This tool finishes a hole rather than drilling it. It removes a thin layer: from 0.05 to 0.15 mm on the diameter in one pass. A smaller allowance produces a smoother wall. Too little allowance is detrimental, as the blades rub against the wall instead of cutting and become dull faster.
Calculation: 79 mm hole from a 78.9 mm initial hole
Allowance on diameter = finished hole diameter 79.0 mm − initial hole diameter 78.9 mm = 0.1 mm. Half of this, or 0.05 mm, is on each wall. This layer is thinner than a sheet of paper. A reamer set to 79.0 mm will remove it in one pass.
| Finished hole [mm] | Initial hole [mm] | Diametral allowance [mm] | Layer thickness at the wall [mm] | Passes |
|---|---|---|---|---|
| 74.0 | 73.9 | 0.1 | 0.05 | 1 |
| 79.0 | 78.9 | 0.1 | 0.05 | 1 |
| 79.0 | 78.8 | 0.2 | 0.1 | 2: set to 78.9, then 79.0 |
| 84.0 | 83.9 | 0.1 | 0.05 | 1 |
The 78 mm drill in the range would leave a 1.0 mm allowance for a 79 mm hole, or 0.5 mm per wall. This is approximately 6.7 times the amount the blades remove in one pass. The reamer is a finishing tool, so remove this amount beforehand by boring the hole. Remove a larger allowance from the initial hole, e.g., 0.2 mm, in two passes: to 78.9 and 79.0 mm.
Tap wrench and lubrication – what to prepare
Tap wrench for a 40 mm square and oil suited to the material
Tap wrench No. 9
The shank square measures 40 mm. Select an adjustable tap wrench to DIN 1814, size No. 9. It accommodates squares from 22 to 45 mm and fits M39–M110 taps. The smaller No. 8 tap wrench has an upper limit of 40 mm, right at the reamer's square size.
With oil or dry
| Workpiece material | Lubrication |
|---|---|
| Steel and cast steel | cutting oil or emulsion |
| Aluminum alloys | cutting oil or emulsion |
| Gray and malleable cast iron | dry |
| Bronze and brass | dry |
Remove chips from the reamer after use. Before adjusting the blades, also clean the body grooves so the blades move evenly.
Adjustable reamer 74-84 mm NRZe requires a bored initial hole and a tap wrench for a 40 mm square. The reamer is 400 mm long, with 123 mm blades. Leave the initial hole 0.05–0.15 mm smaller in diameter than the finished hole. A No. 9 tap wrench, designed for squares from 22 to 45 mm, fits the square. Always turn the reamer clockwise, including when withdrawing it from the hole.
Questions about size selection, tap wrench selection, and the initial hole
Frequently asked questions about hand reaming
Both fit holes from 74 to 84 mm and use the same tap wrench. The 70-85 mm reamer also covers holes from 70 to 74 and from 84 to 85 mm. The 74-84 mm reamer is shorter: 400 mm long versus 510 mm.
A No. 9 adjustable tap wrench, which accepts squares from 22 to 45 mm. The No. 8 tap wrench has a maximum capacity of 40 mm, exactly at the reamer's square size. Both sizes also fit large hand taps, from M25 to M110.
Bore the initial hole to a diameter of 78.85 to 78.95 mm, i.e., 0.05–0.15 mm undersize. A reamer set to 79.0 mm will remove this allowance in one pass. After a 78.8 mm initial hole, ream in two passes: to 78.9 and 79.0 mm.
Clockwise, just as when reaming. Clockwise rotation protects the blades and the hole wall. It also keeps the nuts in place, so the setting does not change.
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Shipping
All orders are delivered by courier company GLS. For orders exceeding 369 PLN gross shipping is FREE
| Courier GLS | Przelew24 / Prepayment | 14,76 zł gross | Delivery time 1 working day |
| Courier GLS | Cash on delivery | 17,26 zł gross | Lead time 1 working day |
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