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HH Roberts / Topwell 4-GL |
The saddle is 22" wide, about 2" wider than the # 3 models. The column is heavier, in fact it is the same as that on the #5 models. The slideways on column and cross slide are box ways with large contact area. |
The top spindle is Towpell's special # 40 taper. There are 3 sets of high precision P4 bearings at the bottom and a single bearing at the top. This gives extra rigidity and vibration resistance. We normally set these up to use Cat-V-40 tools. For comparison, below it is a standard spindle in a Bridgeport type R-8 spindle at the bottom with only 2 high precision bearings at the bottom. |
Click here to download our knee mill catalogue. | Above is the 4-GL with the slideway chip guards removed to show the box ways on the column and the knee. The power feed is standard equipment. The Anilam digital readout shown, is an option. |
Specifications | 4-GL | 4-RG |
Table size | 1070 x 254mm, 1270 x 254 or 1270 x 305229mm 10" x 50", 10" x 54" or 12" x 50" |
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Table travel | 914mm 36 " with optional table |
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Cross travel | 400 mm 15.75 " |
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Knee travel | 406 mm 16 " |
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Quill diameter | 85.725 mm 3 3/8" |
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Quill travel | 127 mm 5" |
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Ram travel | 508 mm 20 " |
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Spindle motor | 3 HP continuous, 4.5 Hp 30 minutes | |
Spindle taper | R8 (Opt.NT-30 or NT-40) | |
Quill power feeds | 0.0381, 0.0762, 0.152 mm / Rev. | |
Spindle speeds | 50 - 4,000 or 75 - 6,000 | Lo 15 - 750 Hi 75 - 6,000 |
Weight | 1550 kgs 3,410 lbs |
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The main differences between this model and the #3 model of the series is the saddle and knee construction. The # 4 models have a wider saddle running on box style ways, while these # 3 models have traditional dovetail ways. The column ways are also box ( or square) ways on the # 4 mills and the # 3 models have dovetail ways. The heads and tables are the same on both. |