Gear 2- Idler or compound gear required for some threading pitches. When present, it is driven by Gear 1 and drives the Screw Gear.

Transcription

1 Introduction: The charts here are an attempt to relate the threading charts from the 9" and 10K model B South Bend lathes to the calculations which were used to create them. Each spreadsheet starts with data taken directly from an SBL gearing chart (shown in yellow). The rightmost columns show the rotation rates of the various parts, ending with the calculated feed rates. Definitions: - Outer gear of the pair driven by the Reversing Assembly, which rotates at the spindle rate. May be changed to alter the threading pitch. 1- Idler or compound gear driven by the and which drives either the or 2, if present. For cutting metric threads 1 is a 100/127T transposing pair. 2- Idler or compound gear required for some threading pitches. When present, it is driven by 1 and drives the. - (or box on the Model A ) The which drives the Lead in Models B & C or the QC box in the model A. - May be changed to alter the threading pitch. Lead - Has 1/8" pitch. Drives the Carriage directly when the half-nuts are engaged for threading. When using power feeds (with the Apron Clutch engaged), the Lead turns the apron gearing. Cross-Feed : Has 1/10" pitch and a 12T driving gear. When using power cross feed (with the Apron Clutch engaged), the Cross Feed drives the Compound Base. Apron ing: In the Models A & B, the Apron gears are used when the apron clutch is engaged and the Selector Lever is set for power feeding. When using the Power Feeds, the leadscrew merely acts as a drive shaft to rotate a worm, which in turn, drives a 36T worm gear in the apron. Power longitudinal feed is achieved by the Apron Pinion gear which meshes with a Rack gear on the lathe bed. The pinion gear has a D.P. of 14, which means that the rack pitch will be Pi/14 inches.

2 Power longitudinal feed rates are determined by the apron gearing. The feed rate is obtained by multiplying the Lead rate x 1/36 x 21/43 to get the pinion gear rate, then x 14 x Pi/14 for the feed rate in inches. Power cross-feed rates are calculated similarly: The cross-feed rate is the Lead rate x 1/36 x 21/22 x 57/12 x 0.1" Accuracy: Both longitudinal and cross feed numbers from the chart are generally within " of the computed values.

3 9 or 10K Model B - English Lead (1/8" pitch) SBL Chart Rev / Spindle Rev Spindle TPI Cross Long. 1 2 Rev. / In. Fig. 2 Lead Feeds Feeds In Out In Out 1 Carriage / / / / /

4 Rotation of 1 2 Lead Motion of Carriage 9 or 10K Model B - English Lead (1/8" pitch) Rev. per Spindle Rev. Rev / Spindle Rev Spindle Example - Rev. per Spindle 4 TPI Spindle x 1 = 1 x N / N1 in 1 x 24 / 80 = x N1 out / N2 in [If present] 0.30 x 80 / 18 = x N2 out / N ScrG [ If 2 present ] x 72 / 48 = x N1 out / N ScrG [ If no 2 ] --- Spindle Rev. / Inch Spindle Rev. / Inch 1 / Lead x 8 TPI 1 / x 8 = 4.0 TPI /18 Set (2) Idler Compound

5 M/M 9 or 10K Models B & C - English Lead (1/8" pitch) - With Metric Transposing Fig. SBL Chart Rev / Spindle Rev Carriage 1 2 In Out In Out 1 2 Lead Spindle Rev. / in. M/M / Spindle Rev

6 9 or 10K Models B & C - English Lead (1/8" pitch) - With Metric Transposing Item 1 2 Lead Motion of Carriage Rev. per Spindle Rev. = 1 ( ) x N / N1 in ( 1) x N1 out / N2 in ( 2) x N2 out / N SG Spindle Rev. / Inch or M/M / Rev. Rev./In. = 1 / (Lead ) x 8 M/M / Rev. = 25.4 / (Rev./In.) Example - Rev. per Spindle 6 M/M = 1 1 x 48 / 127 = x 100 / 72 = x 72 / 20 = Spindle Rev. / Inch or M/M / Rev. 1 / x 8 = Rev. / In / = 6.00 M/M / Rev. Set /18 100/127 (2) Compound Compound

7 TPI Fig. Power Longitudinal Feed Rates - 9 or 10K Model B - English SBL Chart Rev / Spindle Rev Inches / Cross Long. 1 2 Lead Pinion Spindle Rev. 1 2 Feeds Feeds In Out In Out Carriage / / / / /

8 TPI Fig. Power Longitudinal Feed Rates - 9 or 10K Model B - English SBL Chart Rev / Spindle Rev Inches / Cross Long. 1 2 Lead Pinion Spindle Rev. 1 2 Feeds Feeds In Out In Out Carriage Rotation of Rev. per Spindle Rev. = 1 1 ( ) x N / N1 in 2 ( 1) x N1 out / N2 in [If 2 present] Lead ( 2) x N2 out / N ScrG [ If 2 present ] ( 1) x N1 out / N ScrG [ If no 2 ] Example - Rev. per Spindle 4 TPI = 1 1 x 24 / 80 = x 80 / 18 = x 72 / 48 = Pinion (Lead ) / 36 x 21/ / 36 x 21/43 = Motion of Carriage Inches / Spindle Rev. (Apron Pinion) x 14 x Pi / 14 Inches / Spindle Rev x 14 x Pi / 14 =

9 Power Cross Feed Rates - 9 or 10K Model B - English - 1/10" pitch Cross Feed SBL Chart Rev. / Spindle Rev Inches / Spindle Rev. TPI Fig. Cross Feeds Long. Feeds 1 2 Lead Cross Feed 1 2 In Out In Out Compound Rest / / / / /

10 Power Cross Feed Rates - 9 or 10K Model B - English - 1/10" pitch Cross Feed Rotation of Rev. per Spindle Rev. Example - Rev. per Spindle 4 TPI = 1 = 1 1 ( ) x N / N1 in 1 x 24 / 80 = ( 1) x N1 out / N2 in [If 2 present] 0.30 x 80 / 18 = Lead ( 2) x N2 out / N ScrG [ If 2 present ] x 72 / 48 = ( 1) x N1 out / N ScrG [ If no 2 ] --- Cross Feed (Lead ) / 36 x 21/22 x 57/ / 36 x 21/22 x 57/12 = Cross Feed Motion Inches / Spindle Rev. (Cross Feed ) x x 0.1 = Inches / Spindle Rev.

11 9 or 10K Model B - English Lead 80T 80T 18T 72T Figure 1 Figure 2 80T 16T 72T 18T 80T 80T 72T 18T Figure 3 Figure 4

12 9 or 10K Models B & C - English Lead - With metric Transposing 127T 100T 127T 100T 72T Figure 1 Figure 2 127T 100T 100T 72T 18T Figure 3

13 Apron ing for all South Bend 9" & 10K Models A & B Not to Scale Cross Feed - 12T 57T Lathe Bed Rack 43T 22T Pinion 14T-14DP Lead Apron Hand Wheel - 14T Idler 45T Clutch 21T Worm Worm 36T Note: All gears are drawn as 22 Dia. Pitch., except for the Pinion which is 14.